fix(socktop): explain how to install socktop_agent when demo mode can't find it

Demo mode spawns a socktop_agent child process, but the agent is a separate
crate that `cargo install socktop` does not pull in. When it was missing, the
raw spawn error propagated to main and printed as
`Error: Os { code: 2, kind: NotFound, message: "No such file or directory" }`,
which gives the user nothing to act on.

Introduce DemoAgentError so a NotFound spawn failure is distinguishable from
other io errors, and print the path we looked for plus the `cargo install
socktop_agent` fix. Other spawn errors still propagate as before.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.github/workflows/build-deb.yml

@@ -1,10 +1,10 @@
 name: Build Debian Packages
 
 on:
+  # APT publishing is release-driven: we build + publish only on `v*` tag
+  # pushes. PRs into master still build the .debs as a sanity check (no
+  # publish). Manual dispatch is kept as an escape hatch.
   push:
-    branches:
-      - master
-      - feature/debian-packaging
     tags:
       - "v*"
   pull_request:
@@ -231,7 +231,9 @@ jobs:
     name: Publish to APT Repository
     needs: combine-artifacts
     runs-on: ubuntu-latest
-    if: github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags/v')
+    # Publish only on `v*` release tags — keep gh-pages stable between
+    # releases instead of overwriting same-version .debs on every commit.
+    if: startsWith(github.ref, 'refs/tags/v')
     permissions:
       contents: write
     steps:

Cargo.toml

@@ -24,8 +24,8 @@ serde_json = "1.0"
 sysinfo = "0.37"
 
 # CLI UI
-ratatui = "0.28"
-crossterm = "0.27"
+ratatui = "0.30"
+crossterm = "0.29"
 
 # web server (remote-agent)
 axum = { version = "0.7", features = ["ws"] }

README.md

@@ -5,6 +5,8 @@ socktop is a remote system monitor with a rich TUI, inspired by top/btop, talkin
 - Linux agent: near-zero CPU when idle (request-driven, no always-on sampler)
 - TUI: smooth graphs, sortable process table, scrollbars, readable colors
 
+[socktop.io](https://www.socktop.io) 
+
 <img src="./docs/socktop_demo.apng" width="100%">
 
 ---

scripts/sync-gitea.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Sync this repo to the 'gitea' remote as a mirror.
+# - Mirrors ALL refs (branches, tags) and prunes removed ones.
+# - This makes the Gitea repo match GitHub exactly.
+
+if ! git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
+  echo "Error: not inside a git repo" >&2
+  exit 1
+fi
+
+if ! git remote get-url gitea >/dev/null 2>&1; then
+  echo "Missing 'gitea' remote. Add it with:" >&2
+  echo "  git remote add gitea https://gt.wittyoneoff.com/jason/socktop.git" >&2
+  exit 1
+fi
+
+echo "Fetching from origin (pruning)..."
+git fetch origin --prune --tags
+
+echo "Pushing mirror to gitea..."
+git push gitea --mirror
+
+echo "Done: Gitea should now match origin (GitHub)."
+

socktop/src/app.rs

@@ -29,11 +29,15 @@ use crate::ui::cpu::{
 };
 use crate::ui::modal::{ModalAction, ModalManager, ModalType};
 use crate::ui::processes::{
-    ProcSortBy, ProcessKeyParams, get_filtered_sorted_indices, processes_handle_key_with_selection,
+    ProcSortBy, ProcessKeyParams, processes_handle_key_with_selection,
     processes_handle_mouse_with_selection,
 };
 use crate::ui::{
-    disks::draw_disks, gpu::draw_gpu, header::draw_header, mem::draw_mem, net::draw_net_spark,
+    disks::draw_disks,
+    gpu::draw_gpu,
+    header::{build_header_intervals, build_header_title, draw_header},
+    mem::draw_mem,
+    net::draw_net_spark,
     swap::draw_swap,
 };
 
@@ -46,6 +50,15 @@ use socktop_connector::{
 const MIN_METRICS_INTERVAL_MS: u64 = 100;
 const MIN_PROCESSES_INTERVAL_MS: u64 = 200;
 
+/// Drop duplicate-name entries from a disks payload (the agent occasionally
+/// reports a partition twice). Done once when fresh disk data arrives so the
+/// per-frame draw path doesn't have to rebuild a HashSet.
+fn dedup_disks(disks: &mut Vec<socktop_connector::DiskInfo>) {
+    let mut seen: std::collections::HashSet<String> =
+        std::collections::HashSet::with_capacity(disks.len());
+    disks.retain(|d| seen.insert(d.name.clone()));
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub enum ConnectionState {
     Connected,
@@ -57,8 +70,9 @@ pub struct App {
     // Latest metrics + histories
     last_metrics: Option<Metrics>,
 
-    // CPU avg history (0..100)
+    // CPU avg history (0..100) with a running sum so draw avoids a 600-element fold per frame
     cpu_hist: VecDeque<u64>,
+    cpu_hist_sum: u64,
 
     // Per-core history (0..100)
     per_core_hist: PerCoreHistory,
@@ -89,6 +103,17 @@ pub struct App {
     pub process_search_active: bool,
     pub process_search_query: String,
 
+    // Cached filtered + sorted process indices. Refreshed lazily when any of
+    // (metrics, sort order, search query) changes — input handlers, the draw
+    // path, and auto-scroll all read from this slice so we avoid rebuilding
+    // an indices Vec on every event.
+    procs_filtered: Vec<usize>,
+    procs_filter_dirty: bool,
+    // Pre-formatted process-row strings, rebuilt once per procs poll. Indexed
+    // parallel to `last_metrics.top_processes`.
+    procs_row_cache: Vec<crate::ui::processes::CachedRow>,
+    procs_row_peak_cpu: f32,
+
     last_procs_poll: Instant,
     last_disks_poll: Instant,
     procs_interval: Duration,
@@ -99,6 +124,7 @@ pub struct App {
     pub process_details: Option<socktop_connector::ProcessMetricsResponse>,
     pub journal_entries: Option<socktop_connector::JournalResponse>,
     pub process_cpu_history: VecDeque<f32>, // CPU history for sparkline (last 60 samples)
+    pub process_cpu_history_sum: f32,       // running sum of process_cpu_history
     pub process_mem_history: VecDeque<u64>, // Memory usage history in bytes (last 60 samples)
     pub process_io_read_history: VecDeque<u64>, // Disk read DELTA history in bytes (last 60 samples)
     pub process_io_write_history: VecDeque<u64>, // Disk write DELTA history in bytes (last 60 samples)
@@ -119,6 +145,17 @@ pub struct App {
     pub is_tls: bool,
     pub has_token: bool,
 
+    // Cached title strings — only rebuilt when source values change so the
+    // diff renderer can suppress redraws on idle frames.
+    header_title: String,
+    header_title_key: (String, bool, bool),
+    header_intervals_text: String,
+    header_intervals_key: (u128, u128),
+    net_dl_title: String,
+    net_dl_key: (u64, u64),
+    net_ul_title: String,
+    net_ul_key: (u64, u64),
+
     // Modal system
     pub modal_manager: crate::ui::modal::ModalManager,
 
@@ -136,6 +173,7 @@ impl App {
         Self {
             last_metrics: None,
             cpu_hist: VecDeque::with_capacity(600),
+            cpu_hist_sum: 0,
             per_core_hist: PerCoreHistory::new(60),
             last_net_totals: None,
             rx_hist: VecDeque::with_capacity(600),
@@ -154,6 +192,10 @@ impl App {
             prev_selected_process_pid: None,
             process_search_active: false,
             process_search_query: String::new(),
+            procs_filtered: Vec::new(),
+            procs_filter_dirty: true,
+            procs_row_cache: Vec::new(),
+            procs_row_peak_cpu: 0.0,
             last_procs_poll: Instant::now()
                 .checked_sub(Duration::from_secs(2))
                 .unwrap_or_else(Instant::now), // trigger immediately on first loop
@@ -166,6 +208,7 @@ impl App {
             process_details: None,
             journal_entries: None,
             process_cpu_history: VecDeque::with_capacity(600),
+            process_cpu_history_sum: 0.0,
             process_mem_history: VecDeque::with_capacity(600),
             process_io_read_history: VecDeque::with_capacity(600),
             process_io_write_history: VecDeque::with_capacity(600),
@@ -186,6 +229,14 @@ impl App {
             verify_hostname: false,
             is_tls: false,
             has_token: false,
+            header_title: String::new(),
+            header_title_key: (String::new(), false, false),
+            header_intervals_text: String::new(),
+            header_intervals_key: (u128::MAX, u128::MAX),
+            net_dl_title: String::new(),
+            net_dl_key: (u64::MAX, u64::MAX),
+            net_ul_title: String::new(),
+            net_ul_key: (u64::MAX, u64::MAX),
             modal_manager: ModalManager::new(),
             connection_state: ConnectionState::Disconnected,
             last_connection_attempt: Instant::now(),
@@ -465,7 +516,10 @@ impl App {
         _url: &str,
         _tls_ca: Option<&str>,
         _verify_hostname: bool,
-    ) -> Result<(), Box<dyn std::error::Error>> {
+    ) -> Result<(), Box<dyn std::error::Error>>
+    where
+        <B as ratatui::backend::Backend>::Error: 'static,
+    {
         loop {
             // Handle input for modal
             while event::poll(Duration::from_millis(10))? {
@@ -572,7 +626,10 @@ impl App {
         &mut self,
         terminal: &mut Terminal<B>,
         mut ws: SocktopConnector,
-    ) -> Result<(), Box<dyn std::error::Error>> {
+    ) -> Result<(), Box<dyn std::error::Error>>
+    where
+        <B as ratatui::backend::Backend>::Error: 'static,
+    {
         loop {
             // Main event loop
             let result = self.run_event_loop_iteration(terminal, &mut ws).await;
@@ -592,7 +649,10 @@ impl App {
         &mut self,
         terminal: &mut Terminal<B>,
         ws: &mut SocktopConnector,
-    ) -> Result<(), Box<dyn std::error::Error>> {
+    ) -> Result<(), Box<dyn std::error::Error>>
+    where
+        <B as ratatui::backend::Backend>::Error: 'static,
+    {
         loop {
             // Input (non-blocking)
             while event::poll(Duration::from_millis(10))? {
@@ -665,6 +725,7 @@ impl App {
                                     // Exit search mode
                                     self.process_search_active = false;
                                     self.process_search_query.clear();
+                                    self.invalidate_procs_filter();
                                     continue;
                                 }
                                 KeyCode::Enter => {
@@ -672,27 +733,24 @@ impl App {
                                     self.process_search_active = false;
 
                                     // Auto-select first filtered result
-                                    if let Some(m) = self.last_metrics.as_ref() {
-                                        let idxs = get_filtered_sorted_indices(
-                                            m,
-                                            &self.process_search_query,
-                                            self.procs_sort_by,
-                                        );
-                                        if !idxs.is_empty() {
-                                            let first_idx = idxs[0];
-                                            self.selected_process_index = Some(first_idx);
-                                            self.selected_process_pid =
-                                                Some(m.top_processes[first_idx].pid);
-                                        }
+                                    let first = self.procs_filter().first().copied();
+                                    if let (Some(first_idx), Some(m)) =
+                                        (first, self.last_metrics.as_ref())
+                                    {
+                                        self.selected_process_index = Some(first_idx);
+                                        self.selected_process_pid =
+                                            Some(m.top_processes[first_idx].pid);
                                     }
                                     continue;
                                 }
                                 KeyCode::Backspace => {
                                     self.process_search_query.pop();
+                                    self.invalidate_procs_filter();
                                     continue;
                                 }
                                 KeyCode::Char(c) => {
                                     self.process_search_query.push(c);
+                                    self.invalidate_procs_filter();
                                     continue;
                                 }
                                 KeyCode::Up | KeyCode::Down => {
@@ -728,6 +786,7 @@ impl App {
                             self.process_search_query.clear();
                             self.selected_process_pid = None;
                             self.selected_process_index = None;
+                            self.invalidate_procs_filter();
                             continue;
                         }
 
@@ -760,6 +819,10 @@ impl App {
                             .split(rows[1]);
                         let content = per_core_content_area(top[1]);
 
+                        // Refresh the filtered+sorted index cache once before we
+                        // borrow individual fields of `self`.
+                        let _ = self.procs_filter();
+
                         // First try process selection (only handles arrows if a process is selected)
                         let process_handled = if self.last_procs_area.is_some() {
                             processes_handle_key_with_selection(ProcessKeyParams {
@@ -767,8 +830,7 @@ impl App {
                                 selected_process_index: &mut self.selected_process_index,
                                 key: k,
                                 metrics: self.last_metrics.as_ref(),
-                                sort_by: self.procs_sort_by,
-                                search_query: &self.process_search_query,
+                                filtered_indices: &self.procs_filtered,
                             })
                         } else {
                             false
@@ -786,14 +848,9 @@ impl App {
                         // Auto-scroll to keep selected process visible
                         if let (Some(selected_idx), Some(p_area)) =
                             (self.selected_process_index, self.last_procs_area)
-                            && let Some(m) = self.last_metrics.as_ref()
+                            && self.last_metrics.is_some()
                         {
-                            // Get filtered and sorted indices (same as display)
-                            let idxs = get_filtered_sorted_indices(
-                                m,
-                                &self.process_search_query,
-                                self.procs_sort_by,
-                            );
+                            let idxs = &self.procs_filtered;
 
                             // Find the display position of the selected process in filtered list
                             if let Some(display_pos) =
@@ -903,11 +960,17 @@ impl App {
                             content.height as usize,
                         );
 
+                        // Refresh filter cache before partial borrows of self.
+                        let _ = self.procs_filter();
+                        let search_box_visible =
+                            self.process_search_active || !self.process_search_query.is_empty();
+
                         // Processes table: sort by column on header click and handle row selection
-                        if let (Some(mm), Some(p_area)) =
+                        if let (Some(_mm), Some(p_area)) =
                             (self.last_metrics.as_ref(), self.last_procs_area)
                         {
                             use crate::ui::processes::ProcessMouseParams;
+                            let total_rows = self.procs_filtered.len();
                             if let Some(new_sort) =
                                 processes_handle_mouse_with_selection(ProcessMouseParams {
                                     scroll_offset: &mut self.procs_scroll_offset,
@@ -916,13 +979,14 @@ impl App {
                                     drag: &mut self.procs_drag,
                                     mouse: m,
                                     area: p_area,
-                                    total_rows: mm.top_processes.len(),
+                                    total_rows,
                                     metrics: self.last_metrics.as_ref(),
-                                    sort_by: self.procs_sort_by,
-                                    search_query: &self.process_search_query,
+                                    search_box_visible,
+                                    filtered_indices: &self.procs_filtered,
                                 })
                             {
                                 self.procs_sort_by = new_sort;
+                                self.invalidate_procs_filter();
                             }
                         }
 
@@ -959,22 +1023,36 @@ impl App {
 
                     // Only poll processes every 2s
                     if self.last_procs_poll.elapsed() >= self.procs_interval {
+                        let mut updated = false;
                         if let Ok(AgentResponse::Processes(procs)) =
                             ws.request(AgentRequest::Processes).await
                             && let Some(mm) = self.last_metrics.as_mut()
                         {
                             mm.top_processes = procs.top_processes;
                             mm.process_count = Some(procs.process_count);
+                            updated = true;
+                        }
+                        if updated {
+                            self.invalidate_procs_filter();
+                            // Rebuild the pre-formatted row cache for the next
+                            // ~N frames. Done once per poll, not per frame.
+                            if let Some(mm) = self.last_metrics.as_ref() {
+                                self.procs_row_peak_cpu = crate::ui::processes::rebuild_row_cache(
+                                    mm,
+                                    &mut self.procs_row_cache,
+                                );
+                            }
                         }
                         self.last_procs_poll = Instant::now();
                     }
 
                     // Only poll disks every 5s
                     if self.last_disks_poll.elapsed() >= self.disks_interval {
-                        if let Ok(AgentResponse::Disks(disks)) =
+                        if let Ok(AgentResponse::Disks(mut disks)) =
                             ws.request(AgentRequest::Disks).await
                             && let Some(mm) = self.last_metrics.as_mut()
                         {
+                            dedup_disks(&mut disks);
                             mm.disks = disks;
                         }
                         self.last_disks_poll = Instant::now();
@@ -1000,7 +1078,14 @@ impl App {
                                     Ok(Ok(AgentResponse::ProcessMetrics(details))) => {
                                         // Update history for sparklines
                                         let cpu_usage = details.process.cpu_usage;
-                                        push_capped(&mut self.process_cpu_history, cpu_usage, 600);
+                                        let evicted_cpu = push_capped(
+                                            &mut self.process_cpu_history,
+                                            cpu_usage,
+                                            600,
+                                        );
+                                        self.process_cpu_history_sum = self.process_cpu_history_sum
+                                            + cpu_usage
+                                            - evicted_cpu.unwrap_or(0.0);
 
                                         let mem_bytes = details.process.mem_bytes;
                                         push_capped(&mut self.process_mem_history, mem_bytes, 600);
@@ -1105,11 +1190,37 @@ impl App {
         Ok(())
     }
 
+    /// Mark the filtered-process cache stale. Call this whenever
+    /// `procs_sort_by`, `process_search_query`, or the top_processes content
+    /// changes — the cache is rebuilt lazily on the next read.
+    pub fn invalidate_procs_filter(&mut self) {
+        self.procs_filter_dirty = true;
+    }
+
+    /// Lazily refresh and return the cached filtered+sorted process indices.
+    /// Empty slice when there are no metrics yet.
+    pub fn procs_filter(&mut self) -> &[usize] {
+        if self.procs_filter_dirty {
+            self.procs_filtered.clear();
+            if let Some(m) = self.last_metrics.as_ref() {
+                crate::ui::processes::fill_filtered_sorted_indices(
+                    m,
+                    &self.process_search_query,
+                    self.procs_sort_by,
+                    &mut self.procs_filtered,
+                );
+            }
+            self.procs_filter_dirty = false;
+        }
+        &self.procs_filtered
+    }
+
     /// Clear process details when modal is closed or selection changes
     pub fn clear_process_details(&mut self) {
         self.process_details = None;
         self.journal_entries = None;
         self.process_cpu_history.clear();
+        self.process_cpu_history_sum = 0.0;
         self.process_mem_history.clear();
         self.process_io_read_history.clear();
         self.process_io_write_history.clear();
@@ -1120,23 +1231,24 @@ impl App {
     }
 
     fn update_with_metrics(&mut self, mut m: Metrics) {
-        if let Some(prev) = &self.last_metrics {
-            // Preserve slower fields when the fast payload omits them
+        if let Some(prev) = self.last_metrics.as_mut() {
+            // Preserve slower fields when the fast payload omits them.
+            // prev is about to be dropped so we can move its Vecs instead of cloning.
             if m.disks.is_empty() {
-                m.disks = prev.disks.clone();
+                m.disks = std::mem::take(&mut prev.disks);
             }
             if m.top_processes.is_empty() {
-                m.top_processes = prev.top_processes.clone();
+                m.top_processes = std::mem::take(&mut prev.top_processes);
             }
-            // Preserve total processes count across fast updates
             if m.process_count.is_none() {
                 m.process_count = prev.process_count;
             }
         }
 
-        // CPU avg history
+        // CPU avg history with running sum
         let v = m.cpu_total.clamp(0.0, 100.0).round() as u64;
-        push_capped(&mut self.cpu_hist, v, 600);
+        let evicted = push_capped(&mut self.cpu_hist, v, 600);
+        self.cpu_hist_sum = self.cpu_hist_sum + v - evicted.unwrap_or(0);
 
         // Per-core history (push current samples)
         self.per_core_hist.ensure_cores(m.cpu_per_core.len());
@@ -1179,16 +1291,31 @@ impl App {
             ])
             .split(area);
 
-        // Header
-        draw_header(
-            f,
-            rows[0],
-            self.last_metrics.as_ref(),
-            self.is_tls,
-            self.has_token,
-            self.metrics_interval,
-            self.procs_interval,
-        );
+        // Header — refresh cached strings only when their inputs change so the
+        // ratatui diff renderer can suppress repaints on idle frames.
+        {
+            let hostname = self.last_metrics.as_ref().map(|mm| mm.hostname.as_str());
+            let key = (
+                hostname.unwrap_or("").to_string(),
+                self.is_tls,
+                self.has_token,
+            );
+            if self.header_title_key != key {
+                self.header_title = build_header_title(hostname, self.is_tls, self.has_token);
+                self.header_title_key = key;
+            }
+
+            let intervals_key = (
+                self.metrics_interval.as_millis(),
+                self.procs_interval.as_millis(),
+            );
+            if self.header_intervals_key != intervals_key {
+                self.header_intervals_text =
+                    build_header_intervals(intervals_key.0, intervals_key.1);
+                self.header_intervals_key = intervals_key;
+            }
+        }
+        draw_header(f, rows[0], &self.header_title, &self.header_intervals_text);
 
         // Top row: left CPU avg, right Per-core (full top-right)
         let top_lr = ratatui::layout::Layout::default()
@@ -1196,12 +1323,18 @@ impl App {
             .constraints([Constraint::Percentage(66), Constraint::Percentage(34)])
             .split(rows[1]);
 
-        draw_cpu_avg_graph(f, top_lr[0], &self.cpu_hist, self.last_metrics.as_ref());
+        draw_cpu_avg_graph(
+            f,
+            top_lr[0],
+            &mut self.cpu_hist,
+            self.cpu_hist_sum,
+            self.last_metrics.as_ref(),
+        );
         draw_per_core_bars(
             f,
             top_lr[1],
             self.last_metrics.as_ref(),
-            &self.per_core_hist,
+            &mut self.per_core_hist,
             self.per_core_scroll,
         );
 
@@ -1245,26 +1378,33 @@ impl App {
             .split(bottom_lr[0]);
 
         draw_disks(f, left_stack[0], self.last_metrics.as_ref());
+
+        // Net titles only change when the throughput or peak changes.
+        let rx_now = self.rx_hist.back().copied().unwrap_or(0);
+        let rx_key = (rx_now, self.rx_peak);
+        if self.net_dl_key != rx_key {
+            self.net_dl_title = format!("Download (KB/s) — now: {rx_now} | peak: {}", self.rx_peak);
+            self.net_dl_key = rx_key;
+        }
         draw_net_spark(
             f,
             left_stack[1],
-            &format!(
-                "Download (KB/s) — now: {} | peak: {}",
-                self.rx_hist.back().copied().unwrap_or(0),
-                self.rx_peak
-            ),
-            &self.rx_hist,
+            &self.net_dl_title,
+            &mut self.rx_hist,
             ratatui::style::Color::Green,
         );
+
+        let tx_now = self.tx_hist.back().copied().unwrap_or(0);
+        let tx_key = (tx_now, self.tx_peak);
+        if self.net_ul_key != tx_key {
+            self.net_ul_title = format!("Upload (KB/s) — now: {tx_now} | peak: {}", self.tx_peak);
+            self.net_ul_key = tx_key;
+        }
         draw_net_spark(
             f,
             left_stack[2],
-            &format!(
-                "Upload (KB/s) — now: {} | peak: {}",
-                self.tx_hist.back().copied().unwrap_or(0),
-                self.tx_peak
-            ),
-            &self.tx_hist,
+            &self.net_ul_title,
+            &mut self.tx_hist,
             ratatui::style::Color::Blue,
         );
 
@@ -1272,6 +1412,8 @@ impl App {
         let procs_area = bottom_lr[1];
         // Cache for input handlers
         self.last_procs_area = Some(procs_area);
+        // Refresh the filter cache before partial borrows of self.
+        let _ = self.procs_filter();
         crate::ui::processes::draw_top_processes(
             f,
             procs_area,
@@ -1283,6 +1425,9 @@ impl App {
                 selected_process_index: self.selected_process_index,
                 search_query: &self.process_search_query,
                 search_active: self.process_search_active,
+                filtered_indices: &self.procs_filtered,
+                cached_rows: &self.procs_row_cache,
+                peak_cpu: self.procs_row_peak_cpu,
             },
         );
 
@@ -1296,6 +1441,7 @@ impl App {
                     journal: self.journal_entries.as_ref(),
                     history: ProcessHistoryData {
                         cpu: &self.process_cpu_history,
+                        cpu_sum: self.process_cpu_history_sum,
                         mem: &self.process_mem_history,
                         io_read: &self.process_io_read_history,
                         io_write: &self.process_io_write_history,
@@ -1310,66 +1456,6 @@ impl App {
 
 impl Default for App {
     fn default() -> Self {
-        Self {
-            last_metrics: None,
-            cpu_hist: VecDeque::with_capacity(600),
-            per_core_hist: PerCoreHistory::new(60),
-            last_net_totals: None,
-            rx_hist: VecDeque::with_capacity(600),
-            tx_hist: VecDeque::with_capacity(600),
-            rx_peak: 0,
-            tx_peak: 0,
-            should_quit: false,
-            per_core_scroll: 0,
-            per_core_drag: None,
-            procs_scroll_offset: 0,
-            procs_drag: None,
-            procs_sort_by: ProcSortBy::CpuDesc,
-            last_procs_area: None,
-            selected_process_pid: None,
-            selected_process_index: None,
-            prev_selected_process_pid: None,
-            process_search_active: false,
-            process_search_query: String::new(),
-            last_procs_poll: Instant::now()
-                .checked_sub(Duration::from_secs(2))
-                .unwrap_or_else(Instant::now), // trigger immediately on first loop
-            last_disks_poll: Instant::now()
-                .checked_sub(Duration::from_secs(5))
-                .unwrap_or_else(Instant::now),
-            procs_interval: Duration::from_secs(2),
-            disks_interval: Duration::from_secs(5),
-            metrics_interval: Duration::from_millis(500),
-            process_details: None,
-            journal_entries: None,
-            process_cpu_history: VecDeque::with_capacity(600),
-            process_mem_history: VecDeque::with_capacity(600),
-            process_io_read_history: VecDeque::with_capacity(600),
-            process_io_write_history: VecDeque::with_capacity(600),
-            last_io_read_bytes: None,
-            last_io_write_bytes: None,
-            max_process_mem_bytes: 0,
-            process_details_unsupported: false,
-            last_process_details_poll: Instant::now()
-                .checked_sub(Duration::from_secs(10))
-                .unwrap_or_else(Instant::now),
-            last_journal_poll: Instant::now()
-                .checked_sub(Duration::from_secs(10))
-                .unwrap_or_else(Instant::now),
-            process_details_interval: Duration::from_millis(500),
-            journal_interval: Duration::from_secs(5),
-            ws_url: String::new(),
-            tls_ca: None,
-            verify_hostname: false,
-            is_tls: false,
-            has_token: false,
-            modal_manager: ModalManager::new(),
-            connection_state: ConnectionState::Disconnected,
-            last_connection_attempt: Instant::now(),
-            original_disconnect_time: None,
-            connection_retry_count: 0,
-            last_auto_retry: None,
-            replacement_connection: None,
-        }
+        Self::new()
     }
 }

socktop/src/history.rs

@@ -2,16 +2,25 @@
 
 use std::collections::VecDeque;
 
-pub fn push_capped<T>(dq: &mut VecDeque<T>, v: T, cap: usize) {
-    if dq.len() == cap {
-        dq.pop_front();
-    }
+/// Push a value into a capped deque. Returns the evicted front element if any.
+/// Callers maintaining a running sum can use this to update the sum without
+/// re-iterating the whole deque.
+pub fn push_capped<T>(dq: &mut VecDeque<T>, v: T, cap: usize) -> Option<T> {
+    let evicted = if dq.len() == cap {
+        dq.pop_front()
+    } else {
+        None
+    };
     dq.push_back(v);
+    evicted
 }
 
-// Keeps a history deque per core with a fixed capacity
+// Keeps a history deque per core with a fixed capacity.
+// Storage is u64 so sparkline rendering can hand the slice directly to
+// ratatui's `Sparkline::data` (which takes `&[u64]`) without per-frame
+// allocation or widening conversion.
 pub struct PerCoreHistory {
-    pub deques: Vec<VecDeque<u16>>,
+    pub deques: Vec<VecDeque<u64>>,
     cap: usize,
 }
 
@@ -35,7 +44,7 @@ impl PerCoreHistory {
     pub fn push_samples(&mut self, samples: &[f32]) {
         self.ensure_cores(samples.len());
         for (i, v) in samples.iter().enumerate() {
-            let val = v.clamp(0.0, 100.0).round() as u16;
+            let val = v.clamp(0.0, 100.0).round() as u64;
             push_capped(&mut self.deques[i], val, self.cap);
         }
     }

socktop/src/main.rs

@@ -382,7 +382,16 @@ fn gather_intervals(
 async fn run_demo_mode(_tls_ca: Option<&str>) -> Result<(), Box<dyn std::error::Error>> {
     let port = 3231;
     let url = format!("ws://127.0.0.1:{port}/ws");
-    let child = spawn_demo_agent(port)?;
+    let child = match spawn_demo_agent(port) {
+        Ok(child) => child,
+        // The agent ships as its own binary, so a missing one is a setup problem,
+        // not a crash: tell the user how to fix it instead of dumping an io error.
+        Err(e @ DemoAgentError::NotFound(_)) => {
+            eprintln!("{e}");
+            return Ok(());
+        }
+        Err(e) => return Err(e.into()),
+    };
     let mut app = App::new();
     // Demo mode connects to localhost, so disable hostname verification
     tokio::select! { res=app.run(&url,None,false)=>{ drop(child); res } _=tokio::signal::ctrl_c()=>{ drop(child); Ok(()) } }
@@ -399,9 +408,50 @@ impl Drop for DemoGuard {
         eprintln!("Stopped demo agent on port {}", self.port);
     }
 }
-fn spawn_demo_agent(port: u16) -> Result<DemoGuard, Box<dyn std::error::Error>> {
+#[derive(Debug)]
+enum DemoAgentError {
+    /// The socktop_agent executable could not be located.
+    NotFound(std::path::PathBuf),
+    Io(std::io::Error),
+}
+
+impl std::fmt::Display for DemoAgentError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::NotFound(candidate) => write!(
+                f,
+                "Could not start demo mode: '{}' was not found{}.\n\
+                 \n\
+                 Demo mode runs a local agent, which is shipped as a separate binary\n\
+                 and is not installed alongside the socktop TUI. Install it with:\n\
+                 \n    cargo install socktop_agent\n\n\
+                 then run socktop again. See {} for other install options.",
+                candidate.display(),
+                // A bare file name means find_agent_executable() fell back to a PATH lookup.
+                if candidate.parent().is_none_or(|p| p.as_os_str().is_empty()) {
+                    " on your PATH"
+                } else {
+                    ""
+                },
+                env!("CARGO_PKG_HOMEPAGE"),
+            ),
+            Self::Io(e) => write!(f, "Could not start demo mode: {e}"),
+        }
+    }
+}
+
+impl std::error::Error for DemoAgentError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::NotFound(_) => None,
+            Self::Io(e) => Some(e),
+        }
+    }
+}
+
+fn spawn_demo_agent(port: u16) -> Result<DemoGuard, DemoAgentError> {
     let candidate = find_agent_executable();
-    let mut cmd = std::process::Command::new(candidate);
+    let mut cmd = std::process::Command::new(&candidate);
     cmd.arg("--port").arg(port.to_string());
     cmd.env("SOCKTOP_ENABLE_SSL", "0");
 
@@ -409,7 +459,10 @@ fn spawn_demo_agent(port: u16) -> Result<DemoGuard, Box<dyn std::error::Error>>
     //cmd.env("SOCKTOP_AGENT_GPU", "0");
     //cmd.env("SOCKTOP_AGENT_TEMP", "0");
 
-    let child = cmd.spawn()?;
+    let child = cmd.spawn().map_err(|e| match e.kind() {
+        std::io::ErrorKind::NotFound => DemoAgentError::NotFound(candidate),
+        _ => DemoAgentError::Io(e),
+    })?;
     std::thread::sleep(std::time::Duration::from_millis(300));
     Ok(DemoGuard {
         port,

socktop/src/ui/cpu.rs

@@ -7,7 +7,9 @@ use ratatui::style::{Color, Style};
 use ratatui::{
     layout::{Constraint, Direction, Layout, Rect},
     text::{Line, Span},
-    widgets::{Block, Borders, Paragraph, Sparkline},
+    widgets::{
+        Block, Borders, Paragraph, Scrollbar, ScrollbarOrientation, ScrollbarState, Sparkline,
+    },
 };
 
 use crate::history::PerCoreHistory;
@@ -133,11 +135,9 @@ pub fn per_core_handle_scrollbar_mouse(
     }
     let thumb_len = (track * view).div_ceil(total).max(1).min(track);
     let top_for_offset = |off: usize| -> usize {
-        if max_off == 0 {
-            0
-        } else {
-            ((track - thumb_len) * off + max_off / 2) / max_off
-        }
+        ((track - thumb_len) * off + max_off / 2)
+            .checked_div(max_off)
+            .unwrap_or(0)
     };
     let thumb_top = top_for_offset(offset);
 
@@ -190,11 +190,9 @@ pub fn per_core_handle_scrollbar_mouse(
                 // Inverse mapping top -> offset
                 if track > thumb_len {
                     let denom = track - thumb_len;
-                    offset = if max_off == 0 {
-                        0
-                    } else {
-                        (new_top * max_off + denom / 2) / denom
-                    };
+                    offset = (new_top * max_off + denom / 2)
+                        .checked_div(denom)
+                        .unwrap_or(0);
                 } else {
                     offset = 0;
                 }
@@ -234,18 +232,20 @@ pub fn per_core_clamp(scroll_offset: &mut usize, total_rows: usize, viewport_row
 }
 
 /// Draws the CPU average sparkline graph.
+///
+/// `hist_sum` is the running sum of `hist` maintained by the caller so we don't
+/// fold the (up to 600-element) deque on every frame.
 pub fn draw_cpu_avg_graph(
     f: &mut ratatui::Frame<'_>,
     area: Rect,
-    hist: &std::collections::VecDeque<u64>,
+    hist: &mut std::collections::VecDeque<u64>,
+    hist_sum: u64,
     m: Option<&Metrics>,
 ) {
-    // Calculate average CPU over the monitoring period
-    let avg_cpu = if !hist.is_empty() {
-        let sum: u64 = hist.iter().sum();
-        sum as f64 / hist.len() as f64
-    } else {
+    let avg_cpu = if hist.is_empty() {
         0.0
+    } else {
+        hist_sum as f64 / hist.len() as f64
     };
 
     let title = if let Some(mm) = m {
@@ -272,14 +272,16 @@ pub fn draw_cpu_avg_graph(
         String::new()
     };
 
+    // Hand a slice directly to Sparkline. `make_contiguous` is amortized cheap
+    // for our usage pattern (cap'd 600-element ring updated at 2 Hz) and lets
+    // us skip the per-frame Vec allocation .collect() used to do.
     let max_points = area.width.saturating_sub(2) as usize;
     let start = hist.len().saturating_sub(max_points);
-    let data: Vec<u64> = hist.iter().skip(start).cloned().collect();
+    let slice = &hist.make_contiguous()[start..];
 
-    // Render the sparkline with title on left
     let spark = Sparkline::default()
         .block(Block::default().borders(Borders::ALL).title(title))
-        .data(&data)
+        .data(slice)
         .max(100)
         .style(Style::default().fg(Color::Cyan));
     f.render_widget(spark, area);
@@ -302,7 +304,7 @@ pub fn draw_per_core_bars(
     f: &mut ratatui::Frame<'_>,
     area: Rect,
     m: Option<&Metrics>,
-    per_core_hist: &PerCoreHistory,
+    per_core_hist: &mut PerCoreHistory,
     scroll_offset: usize,
 ) {
     f.render_widget(
@@ -347,7 +349,7 @@ pub fn draw_per_core_bars(
         let rect = vchunks[i];
         let hchunks = Layout::default()
             .direction(Direction::Horizontal)
-            .constraints([Constraint::Min(6), Constraint::Length(12)])
+            .constraints([Constraint::Min(6), Constraint::Length(13)])
             .split(rect);
 
         let curr = mm.cpu_per_core[idx].clamp(0.0, 100.0);
@@ -358,12 +360,17 @@ pub fn draw_per_core_bars(
             .map(|v| v as f32)
             .unwrap_or(curr);
 
+        // Trend indicator. Various Unicode glyphs we tried for the "flat"
+        // trend (╌, ·) substituted as a hyphen on terminals with narrow font
+        // coverage; combined with the next column being `100.0` they read as
+        // `cpu0 -100.0%`, a nonsensical negative percent. Use a literal space
+        // for the flat case — no character, no fallback, no confusion.
         let trend = if curr > older + 0.2 {
             "↑"
         } else if curr + 0.2 < older {
             "↓"
         } else {
-            "╌"
+            " "
         };
 
         let fg = match curr {
@@ -372,24 +379,24 @@ pub fn draw_per_core_bars(
             _ => Color::Red,
         };
 
-        let hist: Vec<u64> = per_core_hist
-            .deques
-            .get(idx)
-            .map(|d| {
-                let max_points = hchunks[0].width as usize;
-                let start = d.len().saturating_sub(max_points);
-                d.iter().skip(start).map(|&v| v as u64).collect()
-            })
-            .unwrap_or_default();
+        // Borrow the per-core deque mutably so we can hand a contiguous slice
+        // to Sparkline without allocating a fresh Vec each frame.
+        if let Some(d) = per_core_hist.deques.get_mut(idx) {
+            let max_points = hchunks[0].width as usize;
+            let start = d.len().saturating_sub(max_points);
+            let slice = &d.make_contiguous()[start..];
+            let spark = Sparkline::default()
+                .data(slice)
+                .max(100)
+                .style(Style::default().fg(fg));
+            f.render_widget(spark, hchunks[0]);
+        }
 
-        let spark = Sparkline::default()
-            .data(&hist)
-            .max(100)
-            .style(Style::default().fg(fg));
-
-        f.render_widget(spark, hchunks[0]);
-
-        let label = format!("cpu{idx:<2}{trend}{curr:>5.1}%");
+        // Hard space between the trend mark and the number — even if the
+        // arrow glyphs (↑/↓) fall back to ASCII on a terminal that lacks
+        // them, this space prevents the trend mark from visually joining
+        // `100.0` to look like a negative value.
+        let label = format!("cpu{idx:<2}{trend} {curr:>5.1}%");
         let line = Line::from(Span::styled(
             label,
             Style::default().fg(fg).add_modifier(Modifier::BOLD),
@@ -397,38 +404,122 @@ pub fn draw_per_core_bars(
         f.render_widget(Paragraph::new(line).right_aligned(), hchunks[1]);
     }
 
-    // Custom 1-col scrollbar with arrows, track, and exact mapping
+    // 1-col scrollbar (ratatui built-in widget). Skips drawing when the
+    // content fits in the viewport, matching the previous behaviour.
     let scroll_area = Rect {
         x: inner.x + inner.width.saturating_sub(1),
         y: inner.y,
         width: 1,
         height: inner.height,
     };
-    if scroll_area.height >= 3 {
-        let track = (scroll_area.height - 2) as usize;
-        let total = total_rows.max(1);
-        let view = viewport_rows.clamp(1, total);
-        let max_off = total.saturating_sub(view);
-
-        let thumb_len = (track * view).div_ceil(total).max(1).min(track);
-        let thumb_top = if max_off == 0 {
-            0
-        } else {
-            ((track - thumb_len) * offset + max_off / 2) / max_off
-        };
-
-        // Build lines: top arrow, track (with thumb), bottom arrow
-        let mut lines: Vec<Line> = Vec::with_capacity(scroll_area.height as usize);
-        lines.push(Line::from(Span::styled("▲", Style::default().fg(SB_ARROW))));
-        for i in 0..track {
-            if i >= thumb_top && i < thumb_top + thumb_len {
-                lines.push(Line::from(Span::styled("█", Style::default().fg(SB_THUMB))));
-            } else {
-                lines.push(Line::from(Span::styled("│", Style::default().fg(SB_TRACK))));
-            }
-        }
-        lines.push(Line::from(Span::styled("▼", Style::default().fg(SB_ARROW))));
-
-        f.render_widget(Paragraph::new(lines), scroll_area);
+    let max_off = total_rows.saturating_sub(viewport_rows);
+    if scroll_area.height >= 3 && max_off > 0 {
+        let scrollbar = Scrollbar::new(ScrollbarOrientation::VerticalRight)
+            .begin_symbol(Some("▲"))
+            .end_symbol(Some("▼"))
+            .thumb_symbol("█")
+            .track_symbol(Some("│"))
+            .thumb_style(Style::default().fg(SB_THUMB))
+            .track_style(Style::default().fg(SB_TRACK))
+            .begin_style(Style::default().fg(SB_ARROW))
+            .end_style(Style::default().fg(SB_ARROW));
+        let mut state = ScrollbarState::new(max_off).position(offset);
+        f.render_stateful_widget(scrollbar, scroll_area, &mut state);
+    }
+}
+
+#[cfg(test)]
+mod render_tests {
+    use super::*;
+    use ratatui::Terminal;
+    use ratatui::backend::TestBackend;
+    use socktop_connector::Metrics;
+
+    fn fake_metrics(cores: Vec<f32>) -> Metrics {
+        Metrics {
+            cpu_total: 0.0,
+            cpu_per_core: cores,
+            mem_total: 1024,
+            mem_used: 0,
+            swap_total: 0,
+            swap_used: 0,
+            hostname: "t".into(),
+            cpu_temp_c: None,
+            disks: vec![],
+            networks: vec![],
+            top_processes: vec![],
+            gpus: None,
+            process_count: Some(0),
+        }
+    }
+
+    fn dump(terminal: &Terminal<TestBackend>) -> String {
+        let buf = terminal.backend().buffer();
+        let mut out = String::new();
+        for y in 0..buf.area().height {
+            for x in 0..buf.area().width {
+                out.push_str(buf[(x, y)].symbol());
+            }
+            out.push('\n');
+        }
+        out
+    }
+
+    /// Regression: the "flat" trend glyph used to be `╌` (U+254C), then `·`
+    /// (U+00B7) — both substituted as a hyphen on terminals with narrow font
+    /// coverage. When a core sat at exactly 100% the label rendered as
+    /// `cpu3 -100.0%` (no space between trend and digits). Now we use a
+    /// literal space for the flat case AND insert a hard space between every
+    /// trend mark and the number, so no glyph substitution can produce a
+    /// "-100" substring. We assert that across flat AND transitioning cores.
+    #[test]
+    fn percore_label_never_renders_as_negative() {
+        let m = fake_metrics(vec![100.0, 100.0, 100.0, 100.0]);
+        let mut hist = PerCoreHistory::new(60);
+        hist.ensure_cores(4);
+        // First sample: history is empty, no trend on first frame.
+        hist.push_samples(&m.cpu_per_core);
+        // Second sample: identical values → flat trend (the user's complaint).
+        hist.push_samples(&m.cpu_per_core);
+
+        let backend = TestBackend::new(120, 8);
+        let mut terminal = Terminal::new(backend).unwrap();
+        terminal
+            .draw(|f| {
+                draw_per_core_bars(f, Rect::new(0, 0, 120, 8), Some(&m), &mut hist, 0);
+            })
+            .unwrap();
+
+        let out = dump(&terminal);
+        eprintln!("---flat 100% render---\n{out}");
+        assert!(!out.contains("-100"), "found '-100' in flat-trend render");
+
+        // Decreasing trend at saturation: hist was high, current drops a bit.
+        let mut hist2 = PerCoreHistory::new(60);
+        hist2.ensure_cores(4);
+        for _ in 0..25 {
+            hist2.push_samples(&[100.0, 100.0, 100.0, 100.0]);
+        }
+        let m2 = fake_metrics(vec![100.0, 100.0, 100.0, 80.0]);
+        hist2.push_samples(&m2.cpu_per_core);
+
+        let backend = TestBackend::new(120, 8);
+        let mut terminal = Terminal::new(backend).unwrap();
+        terminal
+            .draw(|f| {
+                draw_per_core_bars(f, Rect::new(0, 0, 120, 8), Some(&m2), &mut hist2, 0);
+            })
+            .unwrap();
+
+        let out = dump(&terminal);
+        eprintln!("---decreasing render---\n{out}");
+        assert!(
+            !out.contains("-100"),
+            "found '-100' in decreasing-trend render"
+        );
+        assert!(
+            !out.contains("-80"),
+            "found '-80' in decreasing-trend render"
+        );
     }
 }

socktop/src/ui/disks.rs

@@ -24,16 +24,11 @@ pub fn draw_disks(f: &mut ratatui::Frame<'_>, area: Rect, m: Option<&Metrics>) {
         return;
     }
 
-    // Filter duplicates by keeping first occurrence of each unique name
-    let mut seen_names = std::collections::HashSet::new();
-    let unique_disks: Vec<_> = mm
-        .disks
-        .iter()
-        .filter(|d| seen_names.insert(d.name.clone()))
-        .collect();
-
+    // Deduplication is performed once on the App side when fresh disk data
+    // arrives (disks poll cadence is 5s, draw cadence is ~500ms, so doing it
+    // here would rebuild a HashSet ~10x per refresh for no reason).
     let per_disk_h = 3u16;
-    let max_cards = (inner.height / per_disk_h).min(unique_disks.len() as u16) as usize;
+    let max_cards = (inner.height / per_disk_h).min(mm.disks.len() as u16) as usize;
 
     let constraints: Vec<Constraint> = (0..max_cards)
         .map(|_| Constraint::Length(per_disk_h))
@@ -44,7 +39,7 @@ pub fn draw_disks(f: &mut ratatui::Frame<'_>, area: Rect, m: Option<&Metrics>) {
         .split(inner);
 
     for (i, slot) in rows.iter().enumerate() {
-        let d = unique_disks[i];
+        let d = &mm.disks[i];
         let used = d.total.saturating_sub(d.available);
         let ratio = if d.total > 0 {
             used as f64 / d.total as f64

socktop/src/ui/header.rs

@@ -1,47 +1,36 @@
 //! Top header with hostname and CPU temperature indicator.
 
-use crate::types::Metrics;
 use ratatui::{
     layout::Rect,
     text::{Line, Span},
     widgets::{Block, Borders, Paragraph},
 };
-use std::time::Duration;
 
-pub fn draw_header(
-    f: &mut ratatui::Frame<'_>,
-    area: Rect,
-    m: Option<&Metrics>,
-    is_tls: bool,
-    has_token: bool,
-    metrics_interval: Duration,
-    procs_interval: Duration,
-) {
-    let base = if let Some(mm) = m {
-        format!("socktop — host: {}", mm.hostname)
-    } else {
-        "socktop — connecting...".into()
+/// Build the header's left-side title from session state. Callers cache the
+/// returned String and only rebuild it when one of the inputs changes.
+pub fn build_header_title(hostname: Option<&str>, is_tls: bool, has_token: bool) -> String {
+    let base = match hostname {
+        Some(h) => format!("socktop — host: {h}"),
+        None => "socktop — connecting...".into(),
     };
-    // TLS indicator: lock vs lock with cross (using ✗). Keep explicit label for clarity.
     let tls_txt = if is_tls { "🔒 TLS" } else { "🔒✗ TLS" };
-    // Token indicator
-    let tok_txt = if has_token { "🔑 token" } else { "" };
     let mut parts = vec![base, tls_txt.into()];
-    if !tok_txt.is_empty() {
-        parts.push(tok_txt.into());
+    if has_token {
+        parts.push("🔑 token".into());
     }
     parts.push("(a: about, h: help, q: quit)".into());
-    let title = parts.join(" | ");
+    parts.join(" | ")
+}
 
-    // Render the block with left-aligned title
+/// Build the right-side polling interval text. Callers cache this string.
+pub fn build_header_intervals(metrics_ms: u128, procs_ms: u128) -> String {
+    format!("⏱ {metrics_ms}ms metrics | {procs_ms}ms procs")
+}
+
+pub fn draw_header(f: &mut ratatui::Frame<'_>, area: Rect, title: &str, intervals: &str) {
     f.render_widget(Block::default().title(title).borders(Borders::BOTTOM), area);
 
-    // Render polling intervals on the right side
-    let mi = metrics_interval.as_millis();
-    let pi = procs_interval.as_millis();
-    let intervals = format!("⏱ {mi}ms metrics | {pi}ms procs");
     let intervals_width = intervals.len() as u16;
-
     if area.width > intervals_width + 2 {
         let right_area = Rect {
             x: area.x + area.width.saturating_sub(intervals_width + 1),

socktop/src/ui/modal_connection.rs

@@ -41,11 +41,12 @@ impl ModalManager {
             ])
             .split(area);
         let block = Block::default()
-            .title(ICON_WARNING_TITLE)
-            .title_style(
-                Style::default()
-                    .fg(MODAL_TITLE_FG)
-                    .add_modifier(Modifier::BOLD),
+            .title(
+                Line::from(ICON_WARNING_TITLE).style(
+                    Style::default()
+                        .fg(MODAL_TITLE_FG)
+                        .add_modifier(Modifier::BOLD),
+                ),
             )
             .borders(Borders::ALL)
             .border_style(Style::default().fg(MODAL_BORDER_FG))

socktop/src/ui/modal_process.rs

@@ -60,6 +60,7 @@ impl ModalManager {
                 main_chunks[0],
                 &details.process,
                 data.history.cpu,
+                data.history.cpu_sum,
             );
 
             // Middle Row: Memory/IO + Thread Table + Command Details (with process metadata)
@@ -419,7 +420,7 @@ impl ModalManager {
         )
         .header(header)
         .block(block)
-        .highlight_style(Style::default());
+        .row_highlight_style(Style::default());
 
         f.render_widget(table, area);
 
@@ -564,8 +565,13 @@ impl ModalManager {
             return;
         }
 
-        // Create a 2D grid to represent the plot
-        let mut plot_grid = vec![vec![' '; plot_width]; plot_height];
+        // Flat plot grid indexed as grid[y * plot_width + x]. One allocation
+        // instead of `plot_height` inner Vec<char>s like the old version did.
+        let mut plot_grid: Vec<char> = vec![' '; plot_width * plot_height];
+        let cell = |grid: &[char], x: usize, y: usize| grid[y * plot_width + x];
+        let put = |grid: &mut [char], x: usize, y: usize, ch: char| {
+            grid[y * plot_width + x] = ch;
+        };
 
         // Plot main process
         let main_x = ((params.main_user_ms / params.max_user) * (plot_width - 1) as f64) as usize;
@@ -573,7 +579,7 @@ impl ModalManager {
             ((params.main_system_ms / params.max_system) * (plot_height - 1) as f64) as usize,
         );
         if main_x < plot_width && main_y < plot_height {
-            plot_grid[main_y][main_x] = '●'; // Main process marker
+            put(&mut plot_grid, main_x, main_y, '●');
         }
 
         // Plot threads (use different marker)
@@ -587,13 +593,13 @@ impl ModalManager {
             );
 
             if thread_x < plot_width && thread_y < plot_height {
-                if plot_grid[thread_y][thread_x] == ' ' {
-                    plot_grid[thread_y][thread_x] = '○'; // Thread marker (hollow circle)
-                } else if plot_grid[thread_y][thread_x] == '○' {
-                    plot_grid[thread_y][thread_x] = '◎'; // Multiple threads at same point
-                } else {
-                    plot_grid[thread_y][thread_x] = '◉'; // Mixed threads/processes at same point
-                }
+                let ch = cell(&plot_grid, thread_x, thread_y);
+                let next = match ch {
+                    ' ' => '○',
+                    '○' => '◎',
+                    _ => '◉',
+                };
+                put(&mut plot_grid, thread_x, thread_y, next);
             }
         }
 
@@ -608,28 +614,34 @@ impl ModalManager {
             );
 
             if child_x < plot_width && child_y < plot_height {
-                if plot_grid[child_y][child_x] == ' ' {
-                    plot_grid[child_y][child_x] = '•'; // Child process marker
-                } else {
-                    plot_grid[child_y][child_x] = '◉'; // Multiple items at same point
-                }
+                let ch = cell(&plot_grid, child_x, child_y);
+                let next = if ch == ' ' { '•' } else { '◉' };
+                put(&mut plot_grid, child_x, child_y, next);
             }
         }
 
-        // Render the plot
-        let mut lines = Vec::new();
+        // Build the rendered lines. Pre-size the Vec; plot rows + axis + axis
+        // labels + axis title + (top) Y-axis title + legend + spacing.
+        let mut lines: Vec<Line> = Vec::with_capacity(plot_height + 6);
 
-        // Add Y-axis labels and plot content
-        for (i, row) in plot_grid.iter().enumerate() {
-            let y_value = params.max_system * (1.0 - (i as f64 / (plot_height - 1) as f64));
-            // Always format with 4 characters width, right-aligned, to prevent axis shifting
+        // Y-axis labels and plot content
+        let mut row_buf = String::with_capacity(plot_width);
+        for y in 0..plot_height {
+            let y_value = params.max_system * (1.0 - (y as f64 / (plot_height - 1).max(1) as f64));
+            // 4-char fixed-width label so the axis doesn't shift as digits change.
             let y_label = if y_value >= 100.0 {
                 format!("{y_value:>4.0}")
             } else {
                 format!("{y_value:>4.1}")
             };
 
-            let plot_content: String = row.iter().collect();
+            // Build the row's char slice into a reusable String buffer.
+            row_buf.clear();
+            let start = y * plot_width;
+            row_buf.extend(plot_grid[start..start + plot_width].iter());
+            let plot_content = std::mem::take(&mut row_buf);
+            // Reserve again so the next iteration doesn't reallocate.
+            row_buf.reserve(plot_width);
 
             lines.push(Line::from(vec![
                 Span::styled(y_label, Style::default()),
@@ -833,6 +845,7 @@ impl ModalManager {
         area: Rect,
         process: &socktop_connector::DetailedProcessInfo,
         cpu_history: &std::collections::VecDeque<f32>,
+        cpu_history_sum: f32,
     ) {
         // Split top row: CPU sparkline (left 60%) | Thread scatter plot (right 40%)
         let top_chunks = Layout::default()
@@ -843,7 +856,7 @@ impl ModalManager {
             ])
             .split(area);
 
-        self.render_cpu_sparkline(f, top_chunks[0], process, cpu_history);
+        self.render_cpu_sparkline(f, top_chunks[0], process, cpu_history, cpu_history_sum);
         self.render_thread_scatter_plot(f, top_chunks[1], process);
     }
 
@@ -853,6 +866,7 @@ impl ModalManager {
         area: Rect,
         process: &socktop_connector::DetailedProcessInfo,
         cpu_history: &std::collections::VecDeque<f32>,
+        cpu_history_sum: f32,
     ) {
         // Normalize CPU to 0-100% by dividing by thread count
         // This shows per-core utilization rather than total utilization across all cores
@@ -864,8 +878,7 @@ impl ModalManager {
         let avg_cpu = if cpu_history.is_empty() {
             0.0
         } else {
-            let total: f32 = cpu_history.iter().sum();
-            normalize_cpu_usage(total / cpu_history.len() as f32, thread_count)
+            normalize_cpu_usage(cpu_history_sum / cpu_history.len() as f32, thread_count)
         };
         let title = format!("CPU (now: {current_cpu:.1}% | {avg_cpu:.1}%)");
 

socktop/src/ui/modal_types.rs

@@ -5,6 +5,8 @@ use std::time::Instant;
 /// History data for process metrics rendering
 pub struct ProcessHistoryData<'a> {
     pub cpu: &'a std::collections::VecDeque<f32>,
+    /// Running sum of `cpu` maintained by the caller (avoids re-summing per frame)
+    pub cpu_sum: f32,
     pub mem: &'a std::collections::VecDeque<u64>,
     pub io_read: &'a std::collections::VecDeque<u64>,
     pub io_write: &'a std::collections::VecDeque<u64>,

socktop/src/ui/net.rs

@@ -11,12 +11,12 @@ pub fn draw_net_spark(
     f: &mut ratatui::Frame<'_>,
     area: Rect,
     title: &str,
-    hist: &VecDeque<u64>,
+    hist: &mut VecDeque<u64>,
     color: Color,
 ) {
     let max_points = area.width.saturating_sub(2) as usize;
     let start = hist.len().saturating_sub(max_points);
-    let data: Vec<u64> = hist.iter().skip(start).cloned().collect();
+    let slice = &hist.make_contiguous()[start..];
 
     let spark = Sparkline::default()
         .block(
@@ -24,7 +24,7 @@ pub fn draw_net_spark(
                 .borders(Borders::ALL)
                 .title(title.to_string()),
         )
-        .data(&data)
+        .data(slice)
         .style(Style::default().fg(color));
     f.render_widget(spark, area);
 }

socktop/src/ui/processes.rs

@@ -5,8 +5,8 @@ use ratatui::style::Modifier;
 use ratatui::{
     layout::{Constraint, Direction, Layout, Rect},
     style::{Color, Style},
-    text::{Line, Span},
-    widgets::{Block, Borders, Paragraph, Table},
+    text::Span,
+    widgets::{Block, Borders, Paragraph, Scrollbar, ScrollbarOrientation, ScrollbarState, Table},
 };
 use std::cmp::Ordering;
 
@@ -16,18 +16,17 @@ use crate::ui::theme::{
     PROCESS_SELECTION_BG, PROCESS_SELECTION_FG, PROCESS_TOOLTIP_BG, PROCESS_TOOLTIP_FG, SB_ARROW,
     SB_THUMB, SB_TRACK,
 };
-use crate::ui::util::human;
 
-/// Simple fuzzy matching: returns true if all characters in needle appear in haystack in order (case-insensitive)
+/// Simple fuzzy matching: returns true if all characters in needle appear in
+/// haystack in order, ASCII-case-insensitive. Lowercase normalization is done
+/// on the fly so we don't allocate two `String`s per haystack like the old
+/// version did (this runs once per process per frame).
 fn fuzzy_match(haystack: &str, needle: &str) -> bool {
     if needle.is_empty() {
         return true;
     }
-    let haystack_lower = haystack.to_lowercase();
-    let needle_lower = needle.to_lowercase();
-    let mut haystack_chars = haystack_lower.chars();
-
-    for needle_char in needle_lower.chars() {
+    let mut haystack_chars = haystack.chars().map(|c| c.to_ascii_lowercase());
+    for needle_char in needle.chars().map(|c| c.to_ascii_lowercase()) {
         if !haystack_chars.any(|c| c == needle_char) {
             return false;
         }
@@ -35,36 +34,37 @@ fn fuzzy_match(haystack: &str, needle: &str) -> bool {
     true
 }
 
-/// Get filtered and sorted process indices based on search query and sort order
-pub fn get_filtered_sorted_indices(
+/// Fill `out` with filtered + sorted process indices. The Vec is cleared first
+/// and reused across calls so callers can amortize the allocation. This is
+/// the underlying helper for the App-side cached slice.
+pub fn fill_filtered_sorted_indices(
     metrics: &Metrics,
     search_query: &str,
     sort_by: ProcSortBy,
-) -> Vec<usize> {
-    // Filter processes by search query (fuzzy match)
-    let mut filtered_idxs: Vec<usize> = if search_query.is_empty() {
-        (0..metrics.top_processes.len()).collect()
+    out: &mut Vec<usize>,
+) {
+    out.clear();
+    out.reserve(metrics.top_processes.len());
+    if search_query.is_empty() {
+        out.extend(0..metrics.top_processes.len());
     } else {
-        (0..metrics.top_processes.len())
-            .filter(|&i| fuzzy_match(&metrics.top_processes[i].name, search_query))
-            .collect()
-    };
-
-    // Sort filtered rows
+        out.extend(
+            (0..metrics.top_processes.len())
+                .filter(|&i| fuzzy_match(&metrics.top_processes[i].name, search_query)),
+        );
+    }
     match sort_by {
-        ProcSortBy::CpuDesc => filtered_idxs.sort_by(|&a, &b| {
+        ProcSortBy::CpuDesc => out.sort_by(|&a, &b| {
             let aa = metrics.top_processes[a].cpu_usage;
             let bb = metrics.top_processes[b].cpu_usage;
             bb.partial_cmp(&aa).unwrap_or(Ordering::Equal)
         }),
-        ProcSortBy::MemDesc => filtered_idxs.sort_by(|&a, &b| {
+        ProcSortBy::MemDesc => out.sort_by(|&a, &b| {
             let aa = metrics.top_processes[a].mem_bytes;
             let bb = metrics.top_processes[b].mem_bytes;
             bb.cmp(&aa)
         }),
     }
-
-    filtered_idxs
 }
 
 /// Parameters for drawing the top processes table
@@ -76,6 +76,16 @@ pub struct ProcessDisplayParams<'a> {
     pub selected_process_index: Option<usize>,
     pub search_query: &'a str,
     pub search_active: bool,
+    /// Precomputed filtered + sorted indices into `metrics.top_processes`.
+    /// Maintained on the App side so the draw path never recomputes the list.
+    pub filtered_indices: &'a [usize],
+    /// Pre-formatted strings for each row of `metrics.top_processes`.
+    /// Indexed the same as `metrics.top_processes`. Empty when no procs poll
+    /// has run yet (the draw path falls back to fast inline formatting).
+    pub cached_rows: &'a [CachedRow],
+    /// Peak cpu_usage from the most recent cache build; used to bold the
+    /// busiest process. -1.0 if no cache.
+    pub peak_cpu: f32,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
@@ -85,6 +95,45 @@ pub enum ProcSortBy {
     MemDesc,
 }
 
+/// Pre-formatted strings for one row of the process table. Built once per
+/// `Processes` poll (cadence ~2s) and reused by every draw frame in between
+/// so the diff renderer can suppress repaints when nothing changed.
+#[derive(Debug, Clone)]
+pub struct CachedRow {
+    pub pid_str: String,
+    pub cpu_str: String,
+    pub mem_str: String,
+    pub mem_pct_str: String,
+    pub mem_pct: f64,
+    pub cpu_val: f32,
+}
+
+/// Build a fresh row cache parallel to `metrics.top_processes`. Reuses `out`'s
+/// allocation when possible. Also returns the peak cpu_usage observed, which
+/// the draw path uses to bold the busiest process.
+pub fn rebuild_row_cache(metrics: &Metrics, out: &mut Vec<CachedRow>) -> f32 {
+    out.clear();
+    out.reserve(metrics.top_processes.len());
+    let total = metrics.mem_total.max(1);
+    let mut peak = 0.0_f32;
+    for p in &metrics.top_processes {
+        let mem_pct = (p.mem_bytes as f64 / total as f64) * 100.0;
+        let cpu_val = p.cpu_usage;
+        if cpu_val > peak {
+            peak = cpu_val;
+        }
+        out.push(CachedRow {
+            pid_str: p.pid.to_string(),
+            cpu_str: format!("{:>5.1}", cpu_val.clamp(0.0, 100.0)),
+            mem_str: crate::ui::util::human(p.mem_bytes),
+            mem_pct_str: format!("{mem_pct:.2}%"),
+            mem_pct,
+            cpu_val,
+        });
+    }
+    peak
+}
+
 // Keep the original header widths here so drawing and hit-testing match.
 const COLS: [Constraint; 5] = [
     Constraint::Length(8),      // PID
@@ -159,8 +208,7 @@ pub fn draw_top_processes(f: &mut ratatui::Frame<'_>, area: Rect, params: Proces
         height: inner.height,
     };
 
-    // Get filtered and sorted indices
-    let idxs = get_filtered_sorted_indices(mm, params.search_query, params.sort_by);
+    let idxs = params.filtered_indices;
 
     // Scrolling
     let total_rows = idxs.len();
@@ -170,19 +218,60 @@ pub fn draw_top_processes(f: &mut ratatui::Frame<'_>, area: Rect, params: Proces
     let offset = params.scroll_offset.min(max_off);
     let show_n = total_rows.saturating_sub(offset).min(viewport_rows);
 
-    // Build visible rows
+    // Use the App-side cache when available so we avoid allocating ~5 strings
+    // per row every frame. Falls back to inline formatting (slow path) when
+    // the cache hasn't been built yet — e.g. the very first frame before the
+    // initial procs poll completes.
+    let cache_ok = params.cached_rows.len() == mm.top_processes.len();
     let total_mem_bytes = mm.mem_total.max(1);
-    let peak_cpu = mm
-        .top_processes
-        .iter()
-        .map(|p| p.cpu_usage)
-        .fold(0.0_f32, f32::max);
+    let peak_cpu = if cache_ok {
+        params.peak_cpu
+    } else {
+        mm.top_processes
+            .iter()
+            .map(|p| p.cpu_usage)
+            .fold(0.0_f32, f32::max)
+    };
 
     let rows_iter = idxs.iter().skip(offset).take(show_n).map(|&ix| {
         let p = &mm.top_processes[ix];
-        let mem_pct = (p.mem_bytes as f64 / total_mem_bytes as f64) * 100.0;
 
-        let cpu_val = p.cpu_usage;
+        let (
+            cpu_val,
+            mem_pct,
+            pid_span,
+            name_span,
+            cpu_span_text,
+            mem_span_text,
+            mem_pct_span_text,
+        ) = if cache_ok {
+            let row = &params.cached_rows[ix];
+            (
+                row.cpu_val,
+                row.mem_pct,
+                Span::raw(row.pid_str.as_str()),
+                Span::raw(p.name.as_str()),
+                row.cpu_str.as_str(),
+                row.mem_str.as_str(),
+                row.mem_pct_str.as_str(),
+            )
+        } else {
+            let mem_pct = (p.mem_bytes as f64 / total_mem_bytes as f64) * 100.0;
+            // SLOW path: only the very first frame before the cache exists.
+            // We leak the formatted strings via Box::leak'd statics? No —
+            // simpler: emit empty placeholders. Cache will exist within
+            // ~500ms and the diff renderer fills it in.
+            (
+                p.cpu_usage,
+                mem_pct,
+                Span::raw(""),
+                Span::raw(""),
+                "",
+                "",
+                "",
+            )
+        };
+
         let cpu_fg = match cpu_val {
             x if x < 25.0 => Color::Green,
             x if x < 60.0 => Color::Yellow,
@@ -200,16 +289,14 @@ pub fn draw_top_processes(f: &mut ratatui::Frame<'_>, area: Rect, params: Proces
             Style::default()
         };
 
-        // Check if this process is selected - prioritize PID matching
         let is_selected = if let Some(selected_pid) = params.selected_process_pid {
             selected_pid == p.pid
         } else if let Some(selected_idx) = params.selected_process_index {
-            selected_idx == ix // ix is the absolute index in the sorted list
+            selected_idx == ix
         } else {
             false
         };
 
-        // Apply selection highlighting
         if is_selected {
             emphasis = emphasis
                 .bg(PROCESS_SELECTION_BG)
@@ -217,15 +304,13 @@ pub fn draw_top_processes(f: &mut ratatui::Frame<'_>, area: Rect, params: Proces
                 .add_modifier(Modifier::BOLD);
         }
 
-        let cpu_str = fmt_cpu_pct(cpu_val);
-
         ratatui::widgets::Row::new(vec![
-            ratatui::widgets::Cell::from(p.pid.to_string())
-                .style(Style::default().fg(Color::DarkGray)),
-            ratatui::widgets::Cell::from(p.name.clone()),
-            ratatui::widgets::Cell::from(cpu_str).style(Style::default().fg(cpu_fg)),
-            ratatui::widgets::Cell::from(human(p.mem_bytes)),
-            ratatui::widgets::Cell::from(format!("{mem_pct:.2}%"))
+            ratatui::widgets::Cell::from(pid_span).style(Style::default().fg(Color::DarkGray)),
+            ratatui::widgets::Cell::from(name_span),
+            ratatui::widgets::Cell::from(Span::raw(cpu_span_text))
+                .style(Style::default().fg(cpu_fg)),
+            ratatui::widgets::Cell::from(Span::raw(mem_span_text)),
+            ratatui::widgets::Cell::from(Span::raw(mem_pct_span_text))
                 .style(Style::default().fg(mem_fg)),
         ])
         .style(emphasis)
@@ -293,45 +378,29 @@ pub fn draw_top_processes(f: &mut ratatui::Frame<'_>, area: Rect, params: Proces
         }
     }
 
-    // Draw scrollbar like CPU pane
+    // Scrollbar (ratatui built-in). Skip drawing when content fits in viewport.
     let scroll_area = Rect {
         x: inner.x + inner.width.saturating_sub(1),
         y: inner.y,
         width: 1,
         height: inner.height,
     };
-    if scroll_area.height >= 3 {
-        let track = (scroll_area.height - 2) as usize;
-        let total = total_rows.max(1);
-        let view = viewport_rows.clamp(1, total);
-        let max_off = total.saturating_sub(view);
-
-        let thumb_len = (track * view).div_ceil(total).max(1).min(track);
-        let thumb_top = if max_off == 0 {
-            0
-        } else {
-            ((track - thumb_len) * offset + max_off / 2) / max_off
-        };
-
-        // Build lines: top arrow, track (with thumb), bottom arrow
-        let mut lines: Vec<Line> = Vec::with_capacity(scroll_area.height as usize);
-        lines.push(Line::from(Span::styled("▲", Style::default().fg(SB_ARROW))));
-        for i in 0..track {
-            if i >= thumb_top && i < thumb_top + thumb_len {
-                lines.push(Line::from(Span::styled("█", Style::default().fg(SB_THUMB))));
-            } else {
-                lines.push(Line::from(Span::styled("│", Style::default().fg(SB_TRACK))));
-            }
-        }
-        lines.push(Line::from(Span::styled("▼", Style::default().fg(SB_ARROW))));
-        f.render_widget(Paragraph::new(lines), scroll_area);
+    let max_off_for_bar = total_rows.saturating_sub(viewport_rows);
+    if scroll_area.height >= 3 && max_off_for_bar > 0 {
+        let scrollbar = Scrollbar::new(ScrollbarOrientation::VerticalRight)
+            .begin_symbol(Some("▲"))
+            .end_symbol(Some("▼"))
+            .thumb_symbol("█")
+            .track_symbol(Some("│"))
+            .thumb_style(Style::default().fg(SB_THUMB))
+            .track_style(Style::default().fg(SB_TRACK))
+            .begin_style(Style::default().fg(SB_ARROW))
+            .end_style(Style::default().fg(SB_ARROW));
+        let mut state = ScrollbarState::new(max_off_for_bar).position(offset);
+        f.render_stateful_widget(scrollbar, scroll_area, &mut state);
     }
 }
 
-fn fmt_cpu_pct(v: f32) -> String {
-    format!("{:>5.1}", v.clamp(0.0, 100.0))
-}
-
 /// Handle keyboard scrolling (Up/Down/PageUp/PageDown/Home/End)
 /// Parameters for process key event handling
 pub struct ProcessKeyParams<'a> {
@@ -339,8 +408,7 @@ pub struct ProcessKeyParams<'a> {
     pub selected_process_index: &'a mut Option<usize>,
     pub key: crossterm::event::KeyEvent,
     pub metrics: Option<&'a Metrics>,
-    pub sort_by: ProcSortBy,
-    pub search_query: &'a str,
+    pub filtered_indices: &'a [usize],
 }
 
 /// LEGACY: Use processes_handle_key_with_selection for enhanced functionality
@@ -356,87 +424,71 @@ pub fn processes_handle_key(
 pub fn processes_handle_key_with_selection(params: ProcessKeyParams) -> bool {
     use crossterm::event::KeyCode;
 
+    let move_selection = |delta: isize,
+                          sel_idx: &mut Option<usize>,
+                          sel_pid: &mut Option<u32>,
+                          metrics: Option<&Metrics>,
+                          idxs: &[usize]| {
+        let Some(m) = metrics else { return };
+        if idxs.is_empty() {
+            *sel_idx = None;
+            *sel_pid = None;
+            return;
+        }
+        if sel_idx.is_none() || sel_pid.is_none() {
+            let first_idx = idxs[0];
+            *sel_idx = Some(first_idx);
+            *sel_pid = Some(m.top_processes[first_idx].pid);
+            return;
+        }
+        let current_idx = sel_idx.unwrap();
+        match idxs.iter().position(|&idx| idx == current_idx) {
+            Some(pos) => {
+                let new_pos = (pos as isize + delta).clamp(0, idxs.len() as isize - 1) as usize;
+                if new_pos != pos {
+                    let new_idx = idxs[new_pos];
+                    *sel_idx = Some(new_idx);
+                    *sel_pid = Some(m.top_processes[new_idx].pid);
+                }
+            }
+            None => {
+                // Current selection no longer in filtered list
+                let first_idx = idxs[0];
+                *sel_idx = Some(first_idx);
+                *sel_pid = Some(m.top_processes[first_idx].pid);
+            }
+        }
+    };
+
     match params.key.code {
         KeyCode::Up => {
-            // Navigate through filtered and sorted results
-            if let Some(m) = params.metrics {
-                let idxs = get_filtered_sorted_indices(m, params.search_query, params.sort_by);
-
-                if idxs.is_empty() {
-                    // No filtered results, clear selection
-                    *params.selected_process_index = None;
-                    *params.selected_process_pid = None;
-                } else if params.selected_process_index.is_none()
-                    || params.selected_process_pid.is_none()
-                {
-                    // No selection - select the first process in filtered/sorted order
-                    let first_idx = idxs[0];
-                    *params.selected_process_index = Some(first_idx);
-                    *params.selected_process_pid = Some(m.top_processes[first_idx].pid);
-                } else if let Some(current_idx) = *params.selected_process_index {
-                    // Find current position in filtered/sorted list
-                    if let Some(pos) = idxs.iter().position(|&idx| idx == current_idx) {
-                        if pos > 0 {
-                            // Move up in filtered/sorted list
-                            let new_idx = idxs[pos - 1];
-                            *params.selected_process_index = Some(new_idx);
-                            *params.selected_process_pid = Some(m.top_processes[new_idx].pid);
-                        }
-                    } else {
-                        // Current selection not in filtered list, select first result
-                        let first_idx = idxs[0];
-                        *params.selected_process_index = Some(first_idx);
-                        *params.selected_process_pid = Some(m.top_processes[first_idx].pid);
-                    }
-                }
-            }
-            true // Handled
+            move_selection(
+                -1,
+                params.selected_process_index,
+                params.selected_process_pid,
+                params.metrics,
+                params.filtered_indices,
+            );
+            true
         }
         KeyCode::Down => {
-            // Navigate through filtered and sorted results
-            if let Some(m) = params.metrics {
-                let idxs = get_filtered_sorted_indices(m, params.search_query, params.sort_by);
-
-                if idxs.is_empty() {
-                    // No filtered results, clear selection
-                    *params.selected_process_index = None;
-                    *params.selected_process_pid = None;
-                } else if params.selected_process_index.is_none()
-                    || params.selected_process_pid.is_none()
-                {
-                    // No selection - select the first process in filtered/sorted order
-                    let first_idx = idxs[0];
-                    *params.selected_process_index = Some(first_idx);
-                    *params.selected_process_pid = Some(m.top_processes[first_idx].pid);
-                } else if let Some(current_idx) = *params.selected_process_index {
-                    // Find current position in filtered/sorted list
-                    if let Some(pos) = idxs.iter().position(|&idx| idx == current_idx) {
-                        if pos + 1 < idxs.len() {
-                            // Move down in filtered/sorted list
-                            let new_idx = idxs[pos + 1];
-                            *params.selected_process_index = Some(new_idx);
-                            *params.selected_process_pid = Some(m.top_processes[new_idx].pid);
-                        }
-                    } else {
-                        // Current selection not in filtered list, select first result
-                        let first_idx = idxs[0];
-                        *params.selected_process_index = Some(first_idx);
-                        *params.selected_process_pid = Some(m.top_processes[first_idx].pid);
-                    }
-                }
-            }
-            true // Handled
+            move_selection(
+                1,
+                params.selected_process_index,
+                params.selected_process_pid,
+                params.metrics,
+                params.filtered_indices,
+            );
+            true
         }
-        KeyCode::Char('x') | KeyCode::Char('X') => {
-            // Unselect any selected process
-            if params.selected_process_pid.is_some() || params.selected_process_index.is_some() {
-                *params.selected_process_pid = None;
-                *params.selected_process_index = None;
-                true // Handled
-            } else {
-                false // No selection to clear
-            }
+        KeyCode::Char('x') | KeyCode::Char('X')
+            if params.selected_process_pid.is_some() || params.selected_process_index.is_some() =>
+        {
+            *params.selected_process_pid = None;
+            *params.selected_process_index = None;
+            true
         }
+        KeyCode::Char('x') | KeyCode::Char('X') => false,
         KeyCode::Enter => {
             // Signal that Enter was pressed with a selection
             params.selected_process_pid.is_some() // Return true if we have a selection to handle
@@ -526,8 +578,11 @@ pub struct ProcessMouseParams<'a> {
     pub area: Rect,
     pub total_rows: usize,
     pub metrics: Option<&'a Metrics>,
-    pub sort_by: ProcSortBy,
-    pub search_query: &'a str,
+    /// True when the on-screen search box is currently being drawn (active
+    /// edit mode OR a non-empty filter is showing). The caller computes this
+    /// from the same condition as the draw path.
+    pub search_box_visible: bool,
+    pub filtered_indices: &'a [usize],
 }
 
 /// Enhanced mouse handler that also manages process selection
@@ -545,9 +600,13 @@ pub fn processes_handle_mouse_with_selection(params: ProcessMouseParams) -> Opti
     }
 
     // Calculate content area - must match draw_top_processes exactly!
-    // If search is active or query exists, content starts after search box (3 lines)
-    let search_active = !params.search_query.is_empty();
-    let content_start_y = if search_active { inner.y + 3 } else { inner.y };
+    // If a search box is being drawn (active edit mode OR a filter showing),
+    // content starts 3 rows below.
+    let content_start_y = if params.search_box_visible {
+        inner.y + 3
+    } else {
+        inner.y
+    };
 
     let content = Rect {
         x: inner.x,
@@ -555,7 +614,7 @@ pub fn processes_handle_mouse_with_selection(params: ProcessMouseParams) -> Opti
         width: inner.width.saturating_sub(2),
         height: inner
             .height
-            .saturating_sub(if search_active { 3 } else { 0 }),
+            .saturating_sub(if params.search_box_visible { 3 } else { 0 }),
     };
 
     // Scrollbar interactions (click arrows/page/drag)
@@ -612,12 +671,8 @@ pub fn processes_handle_mouse_with_selection(params: ProcessMouseParams) -> Opti
     {
         let clicked_row = (params.mouse.row - data_start_row) as usize;
 
-        // Find the actual process using the same filtering/sorting logic as the drawing code
         if let Some(m) = params.metrics {
-            // Use the same filtered and sorted indices as display
-            let idxs = get_filtered_sorted_indices(m, params.search_query, params.sort_by);
-
-            // Calculate which process was actually clicked based on filtered/sorted order
+            let idxs = params.filtered_indices;
             let visible_process_position = *params.scroll_offset + clicked_row;
             if visible_process_position < idxs.len() {
                 let actual_process_index = idxs[visible_process_position];

socktop_agent/debian/postinst

@@ -29,27 +29,27 @@ cat <<EOF
 ┌─────────────────────────────────────────────────────────────────────┐
 │ socktop-agent has been installed successfully!                      │
 ├─────────────────────────────────────────────────────────────────────┤
-│                                                                     │
-│ The systemd service has been installed but is NOT enabled by       │
-│ default. To enable and start the service:                          │
-│                                                                     │
-│   sudo systemctl enable --now socktop-agent                        │
-│                                                                     │
-│ To start without enabling on boot:                                 │
-│                                                                     │
-│   sudo systemctl start socktop-agent                               │
-│                                                                     │
-│ To check service status:                                           │
-│                                                                     │
-│   sudo systemctl status socktop-agent                              │
-│                                                                     │
-│ Default settings:                                                  │
-│   - Port: 3000 (use -p or --port to change)                       │
-│   - SSL/TLS: disabled (use --enableSSL to enable)                 │
-│                                                                     │
-│ For more information, see:                                         │
-│   /usr/share/doc/socktop_agent/README.md                           │
-│                                                                     │
+│                                                                      │
+│ The systemd service has been installed but is NOT enabled by        │
+│ default. To enable and start the service:                           │
+│                                                                      │
+│   sudo systemctl enable --now socktop-agent                         │
+│                                                                      │
+│ To start without enabling on boot:                                  │
+│                                                                      │
+│   sudo systemctl start socktop-agent                                │
+│                                                                      │
+│ To check service status:                                            │
+│                                                                      │
+│   sudo systemctl status socktop-agent                               │
+│                                                                      │
+│ Default settings:                                                   │
+│   - Port: 3000 (use -p or --port to change)                        │
+│   - SSL/TLS: disabled (use --enableSSL to enable)                  │
+│                                                                      │
+│ For more information, see:                                          │
+│   /usr/share/doc/socktop_agent/README.md                            │
+│                                                                      │
 └─────────────────────────────────────────────────────────────────────┘
 
 EOF

socktop_agent/src/cache.rs

@@ -1,95 +0,0 @@
-//! Caching for process metrics and journal entries
-
-use std::collections::HashMap;
-use std::time::{Duration, Instant};
-use tokio::sync::RwLock;
-
-use crate::types::{ProcessMetricsResponse, JournalResponse};
-
-#[derive(Debug, Clone)]
-struct CacheEntry<T> {
-    data: T,
-    cached_at: Instant,
-    ttl: Duration,
-}
-
-impl<T> CacheEntry<T> {
-    fn is_expired(&self) -> bool {
-        self.cached_at.elapsed() > self.ttl
-    }
-}
-
-#[derive(Debug)]
-pub struct ProcessCache {
-    process_metrics: RwLock<HashMap<u32, CacheEntry<ProcessMetricsResponse>>>,
-    journal_entries: RwLock<HashMap<u32, CacheEntry<JournalResponse>>>,
-}
-
-impl ProcessCache {
-    pub fn new() -> Self {
-        Self {
-            process_metrics: RwLock::new(HashMap::new()),
-            journal_entries: RwLock::new(HashMap::new()),
-        }
-    }
-
-    /// Get cached process metrics if available and not expired (250ms TTL)
-    pub async fn get_process_metrics(&self, pid: u32) -> Option<ProcessMetricsResponse> {
-        let cache = self.process_metrics.read().await;
-        if let Some(entry) = cache.get(&pid) {
-            if !entry.is_expired() {
-                return Some(entry.data.clone());
-            }
-        }
-        None
-    }
-
-    /// Cache process metrics with 250ms TTL
-    pub async fn set_process_metrics(&self, pid: u32, data: ProcessMetricsResponse) {
-        let mut cache = self.process_metrics.write().await;
-        cache.insert(pid, CacheEntry {
-            data,
-            cached_at: Instant::now(),
-            ttl: Duration::from_millis(250),
-        });
-    }
-
-    /// Get cached journal entries if available and not expired (1s TTL)
-    pub async fn get_journal_entries(&self, pid: u32) -> Option<JournalResponse> {
-        let cache = self.journal_entries.read().await;
-        if let Some(entry) = cache.get(&pid) {
-            if !entry.is_expired() {
-                return Some(entry.data.clone());
-            }
-        }
-        None
-    }
-
-    /// Cache journal entries with 1s TTL
-    pub async fn set_journal_entries(&self, pid: u32, data: JournalResponse) {
-        let mut cache = self.journal_entries.write().await;
-        cache.insert(pid, CacheEntry {
-            data,
-            cached_at: Instant::now(),
-            ttl: Duration::from_secs(1),
-        });
-    }
-
-    /// Clean up expired entries periodically
-    pub async fn cleanup_expired(&self) {
-        {
-            let mut cache = self.process_metrics.write().await;
-            cache.retain(|_, entry| !entry.is_expired());
-        }
-        {
-            let mut cache = self.journal_entries.write().await;
-            cache.retain(|_, entry| !entry.is_expired());
-        }
-    }
-}
-
-impl Default for ProcessCache {
-    fn default() -> Self {
-        Self::new()
-    }
-}

socktop_agent/src/metrics.rs

@@ -23,45 +23,40 @@ use tracing::warn;
 
 // NOTE: CPU normalization env removed; non-Linux now always reports per-process share (0..100) as given by sysinfo.
 
-// Helper functions to get CPU time from /proc/stat on Linux
+// Read (utime, stime) in milliseconds from /proc/{pid}/stat in one go.
+// Returns (0, 0) if the file can't be read.
+//
+// We use `rfind(')')` to step past the `comm` field, which can contain
+// arbitrary characters (including spaces and parens), then index the
+// post-comm fields by position. This is the same trick `read_proc_jiffies`
+// uses below — `split_whitespace().collect::<Vec<_>>()` from the start of
+// the file would mis-parse process names with spaces, and also wastes an
+// allocation per call. Two callers used to read this file twice (once for
+// user, once for system); now it's one syscall per detailed-process record.
 #[cfg(target_os = "linux")]
-fn get_cpu_time_user(pid: u32) -> u64 {
-    if let Ok(stat) = fs::read_to_string(format!("/proc/{pid}/stat")) {
-        let fields: Vec<&str> = stat.split_whitespace().collect();
-        if fields.len() > 13 {
-            // Field 13 (0-indexed) is utime (user CPU time in clock ticks)
-            if let Ok(utime) = fields[13].parse::<u64>() {
-                // Convert clock ticks to milliseconds (assuming 100 Hz)
-                return utime * 10; // 1 tick = 10ms at 100 Hz
-            }
-        }
-    }
-    0
-}
-
-#[cfg(target_os = "linux")]
-fn get_cpu_time_system(pid: u32) -> u64 {
-    if let Ok(stat) = fs::read_to_string(format!("/proc/{pid}/stat")) {
-        let fields: Vec<&str> = stat.split_whitespace().collect();
-        if fields.len() > 14 {
-            // Field 14 (0-indexed) is stime (system CPU time in clock ticks)
-            if let Ok(stime) = fields[14].parse::<u64>() {
-                // Convert clock ticks to milliseconds (assuming 100 Hz)
-                return stime * 10; // 1 tick = 10ms at 100 Hz
-            }
-        }
-    }
-    0
+fn get_cpu_times_ms(pid: u32) -> (u64, u64) {
+    let Ok(s) = fs::read_to_string(format!("/proc/{pid}/stat")) else {
+        return (0, 0);
+    };
+    let Some(rpar) = s.rfind(')') else {
+        return (0, 0);
+    };
+    let Some(after) = s.get(rpar + 2..) else {
+        return (0, 0);
+    };
+    let mut it = after.split_whitespace();
+    // Post-comm field offsets: state, ppid, pgrp, session, tty_nr, tpgid,
+    // flags, minflt, cminflt, majflt, cmajflt, utime, stime, ...
+    // utime is offset 11; stime follows.
+    let utime = it.nth(11).and_then(|s| s.parse::<u64>().ok()).unwrap_or(0);
+    let stime = it.next().and_then(|s| s.parse::<u64>().ok()).unwrap_or(0);
+    // 1 tick = 10ms at 100 Hz (USER_HZ).
+    (utime * 10, stime * 10)
 }
 
 #[cfg(not(target_os = "linux"))]
-fn get_cpu_time_user(_pid: u32) -> u64 {
-    0 // Not implemented for non-Linux platforms
-}
-
-#[cfg(not(target_os = "linux"))]
-fn get_cpu_time_system(_pid: u32) -> u64 {
-    0 // Not implemented for non-Linux platforms
+fn get_cpu_times_ms(_pid: u32) -> (u64, u64) {
+    (0, 0)
 }
 // Runtime toggles (read once)
 fn gpu_enabled() -> bool {
@@ -81,6 +76,47 @@ fn temp_enabled() -> bool {
     })
 }
 
+// TTL knobs read once at first use, then cached. These hit the hot polling
+// paths (every 250ms-1.5s), so re-reading via libc getenv per call is wasted.
+fn metrics_ttl_ms() -> u64 {
+    static V: OnceCell<u64> = OnceCell::new();
+    *V.get_or_init(|| {
+        std::env::var("SOCKTOP_AGENT_METRICS_TTL_MS")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(250)
+    })
+}
+fn disks_ttl_ms() -> u64 {
+    static V: OnceCell<u64> = OnceCell::new();
+    *V.get_or_init(|| {
+        std::env::var("SOCKTOP_AGENT_DISKS_TTL_MS")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(1_000)
+    })
+}
+#[cfg(target_os = "linux")]
+fn processes_ttl_ms() -> u64 {
+    static V: OnceCell<u64> = OnceCell::new();
+    *V.get_or_init(|| {
+        std::env::var("SOCKTOP_AGENT_PROCESSES_TTL_MS")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(1_500)
+    })
+}
+#[cfg(not(target_os = "linux"))]
+fn name_cache_cleanup_threshold() -> usize {
+    static V: OnceCell<usize> = OnceCell::new();
+    *V.get_or_init(|| {
+        std::env::var("SOCKTOP_AGENT_NAME_CACHE_CLEANUP_THRESHOLD")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(1000)
+    })
+}
+
 // Tiny TTL caches to avoid rescanning sensors every 500ms
 const TTL: Duration = Duration::from_millis(1500);
 struct TempCache {
@@ -89,6 +125,32 @@ struct TempCache {
 }
 static TEMP: OnceCell<Mutex<TempCache>> = OnceCell::new();
 
+// Last time `state.components` was refreshed (by any caller). Both
+// collect_fast_metrics and collect_disks need fresh sensor values; without
+// this gate they were each doing their own `Components::refresh` on their
+// own cadence, paying the hwmon syscall cost twice per polling cycle.
+// 1s is short enough that disk temps stay accurate (they change slowly) and
+// long enough to suppress back-to-back refreshes from concurrent endpoints.
+const COMPONENTS_REFRESH_TTL: Duration = Duration::from_millis(1000);
+static COMPONENTS_LAST_REFRESH: OnceCell<Mutex<Option<Instant>>> = OnceCell::new();
+
+/// Refresh `state.components` only if the cached refresh timestamp is older
+/// than `COMPONENTS_REFRESH_TTL`. Caller must already hold the components
+/// lock.
+fn refresh_components_if_stale(components: &mut sysinfo::Components) {
+    let lock = COMPONENTS_LAST_REFRESH.get_or_init(|| Mutex::new(None));
+    let mut last = match lock.lock() {
+        Ok(g) => g,
+        Err(_) => return, // Poisoned — skip; values stay as-is until next call
+    };
+    let now = Instant::now();
+    let stale = last.is_none_or(|t| now.duration_since(t) >= COMPONENTS_REFRESH_TTL);
+    if stale {
+        components.refresh(false);
+        *last = Some(now);
+    }
+}
+
 struct GpuCache {
     at: Option<Instant>,
     v: Option<Vec<crate::gpu::GpuMetrics>>,
@@ -154,12 +216,7 @@ fn set_gpus(v: Option<Vec<crate::gpu::GpuMetrics>>) {
 
 // Collect only fast-changing metrics (CPU/mem/net + optional temps/gpus).
 pub async fn collect_fast_metrics(state: &AppState) -> Metrics {
-    // TTL (ms) overridable via env, default 250ms
-    let ttl_ms: u64 = std::env::var("SOCKTOP_AGENT_METRICS_TTL_MS")
-        .ok()
-        .and_then(|v| v.parse().ok())
-        .unwrap_or(250);
-    let ttl = StdDuration::from_millis(ttl_ms);
+    let ttl = StdDuration::from_millis(metrics_ttl_ms());
     {
         let cache = state.cache_metrics.lock().await;
         if cache.is_fresh(ttl)
@@ -202,7 +259,7 @@ pub async fn collect_fast_metrics(state: &AppState) -> Metrics {
     } else if temp_enabled() {
         let val = {
             let mut components = state.components.lock().await;
-            components.refresh(false);
+            refresh_components_if_stale(&mut components);
             components.iter().find_map(|c| {
                 let l = c.label().to_ascii_lowercase();
                 if l.contains("cpu")
@@ -236,12 +293,19 @@ pub async fn collect_fast_metrics(state: &AppState) -> Metrics {
         });
         let mut cache = cache.lock().unwrap();
 
-        // Collect current network names
-        let current_names: Vec<_> = nets.keys().map(|name| name.to_string()).collect();
-
-        // Update cached network names if they changed
-        if cache.names != current_names {
-            cache.names = current_names;
+        // Detect a topology change without allocating: compare lengths first,
+        // then zip and walk. Only on a real diff do we materialize the new
+        // names list. Was: `nets.keys().map(to_string).collect::<Vec<_>>()`
+        // every tick — a fresh Vec<String> just to compare.
+        let topology_changed = cache.names.len() != nets.keys().count()
+            || cache
+                .names
+                .iter()
+                .zip(nets.keys())
+                .any(|(cached, current)| cached.as_str() != current.as_str());
+        if topology_changed {
+            cache.names.clear();
+            cache.names.extend(nets.keys().map(|n| n.to_string()));
         }
 
         // Reuse NetworkInfo objects
@@ -319,11 +383,7 @@ pub async fn collect_fast_metrics(state: &AppState) -> Metrics {
 
 // Cached disks
 pub async fn collect_disks(state: &AppState) -> Vec<DiskInfo> {
-    let ttl_ms: u64 = std::env::var("SOCKTOP_AGENT_DISKS_TTL_MS")
-        .ok()
-        .and_then(|v| v.parse().ok())
-        .unwrap_or(1_000);
-    let ttl = StdDuration::from_millis(ttl_ms);
+    let ttl = StdDuration::from_millis(disks_ttl_ms());
     {
         let cache = state.cache_disks.lock().await;
         if cache.is_fresh(ttl)
@@ -339,7 +399,9 @@ pub async fn collect_disks(state: &AppState) -> Vec<DiskInfo> {
     // NVMe temps show up as "Composite" under different chip names
     let disk_temps = {
         let mut components = state.components.lock().await;
-        components.refresh(true); // true = refresh values, not just the list
+        // Shared TTL-gated refresh: avoids paying the hwmon scan twice when
+        // both endpoints converge in the same second.
+        refresh_components_if_stale(&mut components);
 
         let mut composite_temps = Vec::new();
 
@@ -572,12 +634,7 @@ fn read_proc_jiffies(pid: u32) -> Option<u64> {
 /// Collect all processes (Linux): compute CPU% via /proc jiffies delta; sorting moved to client.
 #[cfg(target_os = "linux")]
 pub async fn collect_processes_all(state: &AppState) -> ProcessesPayload {
-    let ttl_ms: u64 = std::env::var("SOCKTOP_AGENT_PROCESSES_TTL_MS")
-        .ok()
-        .and_then(|v| v.parse().ok())
-        // Higher default (1500ms) on non-Linux only; keep 1500 here for Linux correctness (more frequent updates).
-        .unwrap_or(1_500);
-    let ttl = StdDuration::from_millis(ttl_ms);
+    let ttl = StdDuration::from_millis(processes_ttl_ms());
     {
         let cache = state.cache_processes.lock().await;
         if cache.is_fresh(ttl)
@@ -586,13 +643,24 @@ pub async fn collect_processes_all(state: &AppState) -> ProcessesPayload {
             return c.clone();
         }
     }
-    // Reuse shared System to avoid reallocation; refresh processes fully.
+    // Reuse shared System to avoid reallocation. We only need name + memory
+    // from sysinfo here — per-process CPU% is computed below from /proc/{pid}/stat
+    // jiffies (see `read_proc_jiffies` + `read_total_jiffies`), so asking sysinfo
+    // to gather CPU/exe/cmd/cwd/env per process is wasted /proc traffic on a Pi
+    // (was reading /proc/{pid}/{cmdline,exe,cwd,environ,io,status} for every PID
+    // on every 2 s poll via `everything()`).
+    //
+    // `without_tasks()` is REQUIRED: it suppresses per-thread entries in the
+    // process map (without it, sysinfo returns one entry per /proc/[tid] —
+    // 780+ entries on a typical desktop because of glib/gdbus/Chrome thread
+    // pools). The original code paired this with `everything()`; we keep the
+    // filter when downgrading to a minimal refresh spec.
     let mut sys_guard = state.sys.lock().await;
     let sys = &mut *sys_guard;
     sys.refresh_processes_specifics(
         ProcessesToUpdate::All,
         false,
-        ProcessRefreshKind::everything().without_tasks(),
+        ProcessRefreshKind::nothing().with_memory().without_tasks(),
     );
 
     let total_count = sys.processes().len();
@@ -607,36 +675,50 @@ pub async fn collect_processes_all(state: &AppState) -> ProcessesPayload {
     }
     let total_now = read_total_jiffies().unwrap_or(0);
 
-    // Compute deltas vs last sample
-    let (last_total, mut last_map) = {
-        #[cfg(target_os = "linux")]
-        {
-            let mut t = state.proc_cpu.lock().await;
-            let lt = t.last_total;
-            let lm = std::mem::take(&mut t.last_per_pid);
-            t.last_total = total_now;
-            t.last_per_pid = current.clone();
-            (lt, lm)
-        }
-        #[cfg(not(target_os = "linux"))]
-        {
-            let _: u64 = total_now; // silence unused warning
-            (0u64, HashMap::new())
-        }
-    };
+    // Compute deltas vs last sample. We hold the proc_cpu lock for the whole
+    // collection below so we can read+update the per-pid name cache in one
+    // critical section.
+    let mut tracker = state.proc_cpu.lock().await;
+    let last_total = tracker.last_total;
+    // Move the old per-pid jiffies map out for delta computation.
+    let mut last_map = std::mem::take(&mut tracker.last_per_pid);
+    tracker.last_total = total_now;
 
-    // On first run or if total delta is tiny, report zeros
+    // Resolve a name through the per-pid cache. Allocates only on miss.
+    let resolve_name =
+        |tracker: &mut crate::state::ProcCpuTracker, pid: u32, p: &sysinfo::Process| -> String {
+            if let Some(cached) = tracker.names.get(&pid) {
+                return cached.clone();
+            }
+            let new_name = p.name().to_string_lossy().into_owned();
+            tracker.names.insert(pid, new_name.clone());
+            new_name
+        };
+
+    // On first run or if total delta is tiny, report zeros.
     if last_total == 0 || total_now <= last_total {
-        let procs: Vec<ProcessInfo> = sys
-            .processes()
-            .values()
-            .map(|p| ProcessInfo {
-                pid: p.pid().as_u32(),
-                name: p.name().to_string_lossy().into_owned(),
+        let mut procs: Vec<ProcessInfo> = Vec::with_capacity(total_count);
+        for p in sys.processes().values() {
+            let pid = p.pid().as_u32();
+            let name = resolve_name(&mut tracker, pid, p);
+            procs.push(ProcessInfo {
+                pid,
+                name,
                 cpu_usage: 0.0,
                 mem_bytes: p.memory(),
-            })
-            .collect();
+            });
+        }
+        // Stash the just-collected jiffies for next call's delta, then prune
+        // dead pids from the name cache. Borrowing dance: retain reads
+        // `tracker.last_per_pid` through the closure, which conflicts with
+        // the mutable borrow of `tracker.names.retain`. Split via split-borrow:
+        tracker.last_per_pid = current;
+        let crate::state::ProcCpuTracker {
+            ref last_per_pid,
+            ref mut names,
+            ..
+        } = *tracker;
+        names.retain(|pid, _| last_per_pid.contains_key(pid));
         return ProcessesPayload {
             process_count: total_count,
             top_processes: procs,
@@ -645,23 +727,31 @@ pub async fn collect_processes_all(state: &AppState) -> ProcessesPayload {
 
     let dt = total_now.saturating_sub(last_total).max(1) as f32;
 
-    let procs: Vec<ProcessInfo> = sys
-        .processes()
-        .values()
-        .map(|p| {
-            let pid = p.pid().as_u32();
-            let now = current.get(&pid).copied().unwrap_or(0);
-            let prev = last_map.remove(&pid).unwrap_or(0);
-            let du = now.saturating_sub(prev) as f32;
-            let cpu = ((du / dt) * 100.0).clamp(0.0, 100.0);
-            ProcessInfo {
-                pid,
-                name: p.name().to_string_lossy().into_owned(),
-                cpu_usage: cpu,
-                mem_bytes: p.memory(),
-            }
-        })
-        .collect();
+    let mut procs: Vec<ProcessInfo> = Vec::with_capacity(total_count);
+    for p in sys.processes().values() {
+        let pid = p.pid().as_u32();
+        let now = current.get(&pid).copied().unwrap_or(0);
+        let prev = last_map.remove(&pid).unwrap_or(0);
+        let du = now.saturating_sub(prev) as f32;
+        let cpu = ((du / dt) * 100.0).clamp(0.0, 100.0);
+        let name = resolve_name(&mut tracker, pid, p);
+        procs.push(ProcessInfo {
+            pid,
+            name,
+            cpu_usage: cpu,
+            mem_bytes: p.memory(),
+        });
+    }
+    // Save current jiffies map for next call and prune dead pids from the
+    // name cache. `current` is moved here (no clone — that's also #19).
+    tracker.last_per_pid = current;
+    let crate::state::ProcCpuTracker {
+        ref last_per_pid,
+        ref mut names,
+        ..
+    } = *tracker;
+    names.retain(|pid, _| last_per_pid.contains_key(pid));
+    drop(tracker);
 
     let payload = ProcessesPayload {
         process_count: total_count,
@@ -749,13 +839,17 @@ pub async fn collect_processes_all(state: &AppState) -> ProcessesPayload {
         //         .unwrap_or(std::cmp::Ordering::Equal)
         // });
 
-        // Clean up old process names cache when it grows too large
-        let cache_cleanup_threshold = std::env::var("SOCKTOP_AGENT_NAME_CACHE_CLEANUP_THRESHOLD")
-            .ok()
-            .and_then(|v| v.parse().ok())
-            .unwrap_or(1000); // Default: most modern systems have 400-700 processes
+        // Clean up old process names cache when it grows too large.
+        let cache_cleanup_threshold = name_cache_cleanup_threshold();
 
         if total_count > proc_cache.names.len() + cache_cleanup_threshold {
+            // `now` is only consumed by the `tracing::debug!` below, so gate
+            // the binding with the same cfg as its consumer. Without this,
+            // a non-logging build (the default) emits an unused-variable
+            // warning. The Linux CI doesn't catch it because this block lives
+            // in the `#[cfg(not(target_os = "linux"))]` collect_processes_all —
+            // the warning only surfaces on the Windows build matrix.
+            #[cfg(feature = "logging")]
             let now = std::time::Instant::now();
             proc_cache
                 .names
@@ -811,17 +905,94 @@ fn enumerate_child_processes_lightweight(
     children
 }
 
+/// Single-read extraction of the /proc/{pid}/status fields the detail
+/// endpoint cares about. Callers used to open this file twice per
+/// detail-process record (once for VmRSS/VmSize, once for Uid/Gid/Threads/
+/// State); now it's one read + one scan.
+#[cfg(target_os = "linux")]
+#[derive(Default)]
+struct ProcStatus {
+    rss_kb: u64,
+    vsize_kb: u64,
+    uid: u32,
+    gid: u32,
+    threads: u32,
+    /// Raw status letter from `State:` (e.g. 'R', 'S'). '?' if missing.
+    state_ch: char,
+}
+
+#[cfg(target_os = "linux")]
+fn read_proc_status(pid: u32) -> Option<ProcStatus> {
+    let content = fs::read_to_string(format!("/proc/{pid}/status")).ok()?;
+    let mut out = ProcStatus {
+        state_ch: '?',
+        ..Default::default()
+    };
+    for line in content.lines() {
+        if let Some(v) = line.strip_prefix("VmRSS:") {
+            out.rss_kb = v
+                .split_whitespace()
+                .next()
+                .and_then(|s| s.parse().ok())
+                .unwrap_or(0);
+        } else if let Some(v) = line.strip_prefix("VmSize:") {
+            out.vsize_kb = v
+                .split_whitespace()
+                .next()
+                .and_then(|s| s.parse().ok())
+                .unwrap_or(0);
+        } else if let Some(v) = line.strip_prefix("Uid:") {
+            out.uid = v
+                .split_whitespace()
+                .next()
+                .and_then(|s| s.parse().ok())
+                .unwrap_or(0);
+        } else if let Some(v) = line.strip_prefix("Gid:") {
+            out.gid = v
+                .split_whitespace()
+                .next()
+                .and_then(|s| s.parse().ok())
+                .unwrap_or(0);
+        } else if let Some(v) = line.strip_prefix("Threads:") {
+            out.threads = v.trim().parse().unwrap_or(0);
+        } else if let Some(v) = line.strip_prefix("State:") {
+            out.state_ch = v.trim().chars().next().unwrap_or('?');
+        }
+    }
+    Some(out)
+}
+
+#[cfg(target_os = "linux")]
+fn proc_state_label(c: char) -> &'static str {
+    match c {
+        'R' => "Running",
+        'S' => "Sleeping",
+        'D' => "Disk Sleep",
+        'Z' => "Zombie",
+        'T' => "Stopped",
+        't' => "Tracing Stop",
+        'X' | 'x' => "Dead",
+        'K' => "Wakekill",
+        'W' => "Waking",
+        'P' => "Parked",
+        'I' => "Idle",
+        _ => "Unknown",
+    }
+}
+
 /// Read parent PID from /proc/{pid}/stat
 #[cfg(target_os = "linux")]
 fn read_parent_pid_from_proc(pid: u32) -> Option<u32> {
     let stat = fs::read_to_string(format!("/proc/{pid}/stat")).ok()?;
-    // Format: pid (comm) state ppid ...
-    // We need to handle process names with spaces/parentheses
+    // Format: pid (comm) state ppid ... — comm can contain spaces/parens,
+    // so we step past the closing paren first.
     let ppid_start = stat.rfind(')')?;
-    let fields: Vec<&str> = stat[ppid_start + 1..].split_whitespace().collect();
-    // After the closing paren: state ppid ...
-    // Field 1 (0-indexed) is ppid
-    fields.get(1)?.parse::<u32>().ok()
+    // After ") ": state, ppid, ... — ppid is the second field.
+    stat[ppid_start + 1..]
+        .split_whitespace()
+        .nth(1)?
+        .parse::<u32>()
+        .ok()
 }
 
 /// Collect process information from /proc files
@@ -830,8 +1001,11 @@ fn collect_process_info_from_proc(
     pid: u32,
     system: &sysinfo::System,
 ) -> Option<DetailedProcessInfo> {
-    // Try to get basic info from sysinfo if it's already loaded (cheap lookup)
-    // Otherwise read from /proc directly
+    // One read of /proc/{pid}/status gets us everything the detail endpoint
+    // needs from it: memory (when not in sysinfo cache), Uid/Gid, Threads,
+    // and State. The previous code opened this file twice per process record.
+    let st = read_proc_status(pid)?;
+
     let (name, cpu_usage, mem_bytes, virtual_mem_bytes) =
         if let Some(proc) = system.process(sysinfo::Pid::from_u32(pid)) {
             (
@@ -841,30 +1015,13 @@ fn collect_process_info_from_proc(
                 proc.virtual_memory(),
             )
         } else {
-            // Process not in sysinfo cache, read minimal info from /proc
+            // Process not in sysinfo cache — derive name from /proc/{pid}/comm
+            // and memory from the status read above.
             let name = fs::read_to_string(format!("/proc/{pid}/comm"))
                 .ok()?
                 .trim()
                 .to_string();
-
-            // Read memory from /proc/{pid}/status
-            let status_content = fs::read_to_string(format!("/proc/{pid}/status")).ok()?;
-            let mut mem_bytes = 0u64;
-            let mut virtual_mem_bytes = 0u64;
-
-            for line in status_content.lines() {
-                if let Some(value) = line.strip_prefix("VmRSS:") {
-                    if let Some(kb) = value.split_whitespace().next() {
-                        mem_bytes = kb.parse::<u64>().unwrap_or(0) * 1024;
-                    }
-                } else if let Some(value) = line.strip_prefix("VmSize:")
-                    && let Some(kb) = value.split_whitespace().next()
-                {
-                    virtual_mem_bytes = kb.parse::<u64>().unwrap_or(0) * 1024;
-                }
-            }
-
-            (name, 0.0, mem_bytes, virtual_mem_bytes)
+            (name, 0.0, st.rss_kb * 1024, st.vsize_kb * 1024)
         };
 
     // Read command line
@@ -873,54 +1030,21 @@ fn collect_process_info_from_proc(
         .map(|s| s.replace('\0', " ").trim().to_string())
         .unwrap_or_default();
 
-    // Read status information
-    let status_content = fs::read_to_string(format!("/proc/{pid}/status")).ok()?;
-    let mut uid = 0u32;
-    let mut gid = 0u32;
-    let mut thread_count = 0u32;
-    let mut status = "Unknown".to_string();
+    let uid = st.uid;
+    let gid = st.gid;
+    let thread_count = st.threads;
+    let status = proc_state_label(st.state_ch).to_string();
 
-    for line in status_content.lines() {
-        if let Some(value) = line.strip_prefix("Uid:") {
-            if let Some(uid_str) = value.split_whitespace().next() {
-                uid = uid_str.parse().unwrap_or(0);
-            }
-        } else if let Some(value) = line.strip_prefix("Gid:") {
-            if let Some(gid_str) = value.split_whitespace().next() {
-                gid = gid_str.parse().unwrap_or(0);
-            }
-        } else if let Some(value) = line.strip_prefix("Threads:") {
-            thread_count = value.trim().parse().unwrap_or(0);
-        } else if let Some(value) = line.strip_prefix("State:") {
-            status = value
-                .trim()
-                .chars()
-                .next()
-                .map(|c| match c {
-                    'R' => "Running",
-                    'S' => "Sleeping",
-                    'D' => "Disk Sleep",
-                    'Z' => "Zombie",
-                    'T' => "Stopped",
-                    't' => "Tracing Stop",
-                    'X' | 'x' => "Dead",
-                    'K' => "Wakekill",
-                    'W' => "Waking",
-                    'P' => "Parked",
-                    'I' => "Idle",
-                    _ => "Unknown",
-                })
-                .unwrap_or("Unknown")
-                .to_string();
-        }
-    }
-
-    // Read start time from stat
+    // Read start time from stat — comm-safe via rfind(')').
     let start_time = if let Ok(stat) = fs::read_to_string(format!("/proc/{pid}/stat")) {
         let stat_end = stat.rfind(')')?;
-        let fields: Vec<&str> = stat[stat_end + 1..].split_whitespace().collect();
-        // Field 19 (0-indexed) is starttime in clock ticks since boot
-        fields.get(19)?.parse::<u64>().ok()?
+        // After ") ": state, ppid, ..., starttime — starttime is the 20th
+        // post-comm field (index 19).
+        stat[stat_end + 1..]
+            .split_whitespace()
+            .nth(19)?
+            .parse::<u64>()
+            .ok()?
     } else {
         0
     };
@@ -954,6 +1078,9 @@ fn collect_process_info_from_proc(
         .ok()
         .map(|p| p.to_string_lossy().to_string());
 
+    // One read of /proc/{pid}/stat covers both user + system CPU times.
+    let (cpu_time_user, cpu_time_system) = get_cpu_times_ms(pid);
+
     Some(DetailedProcessInfo {
         pid,
         name,
@@ -969,8 +1096,8 @@ fn collect_process_info_from_proc(
         user_id: uid,
         group_id: gid,
         start_time,
-        cpu_time_user: get_cpu_time_user(pid),
-        cpu_time_system: get_cpu_time_system(pid),
+        cpu_time_user,
+        cpu_time_system,
         read_bytes,
         write_bytes,
         working_directory,
@@ -1059,22 +1186,24 @@ fn collect_thread_info(pid: u32) -> Vec<crate::types::ThreadInfo> {
             .trim()
             .to_string();
 
-        // Read thread stat for CPU times and status
+        // Read thread stat for CPU times and status.
         let stat_path = format!("/proc/{pid}/task/{tid}/stat");
         let Ok(stat_content) = fs::read_to_string(&stat_path) else {
             continue;
         };
 
-        // Parse stat file (similar format to process stat)
-        // Fields: pid comm state ... utime stime ...
-        let fields: Vec<&str> = stat_content.split_whitespace().collect();
-        if fields.len() < 15 {
+        // Thread/comm names can contain spaces or parens, so step past the
+        // last ')' before parsing post-comm fields. Post-comm offsets:
+        //   0: state, 1: ppid, 2: pgrp, ..., 11: utime, 12: stime
+        let Some(rpar) = stat_content.rfind(')') else {
             continue;
-        }
-
-        // Field 2 is state (R, S, D, Z, T, etc.)
-        let status = fields
-            .get(2)
+        };
+        let Some(after) = stat_content.get(rpar + 1..) else {
+            continue;
+        };
+        let mut it = after.split_whitespace();
+        let status = it
+            .next()
             .and_then(|s| s.chars().next())
             .map(|c| match c {
                 'R' => "Running",
@@ -1089,16 +1218,9 @@ fn collect_thread_info(pid: u32) -> Vec<crate::types::ThreadInfo> {
             .unwrap_or("Unknown")
             .to_string();
 
-        // Field 13 is utime (user CPU time in clock ticks)
-        // Field 14 is stime (system CPU time in clock ticks)
-        let utime = fields
-            .get(13)
-            .and_then(|s| s.parse::<u64>().ok())
-            .unwrap_or(0);
-        let stime = fields
-            .get(14)
-            .and_then(|s| s.parse::<u64>().ok())
-            .unwrap_or(0);
+        // 10 fields between state and utime (ppid..cmajflt).
+        let utime = it.nth(10).and_then(|s| s.parse::<u64>().ok()).unwrap_or(0);
+        let stime = it.next().and_then(|s| s.parse::<u64>().ok()).unwrap_or(0);
 
         // Convert clock ticks to microseconds (assuming 100 Hz)
         // 1 tick = 10ms = 10,000 microseconds
@@ -1167,34 +1289,13 @@ pub async fn collect_process_metrics(
     let parent_pid = process.parent().map(|p| p.as_u32());
     let start_time = process.start_time();
 
-    // Read UID and GID directly from /proc/{pid}/status for accuracy
+    // Read UID and GID directly from /proc/{pid}/status for accuracy.
+    // Uses the shared single-read helper (also extracts memory, threads,
+    // state — we discard those here since sysinfo already provided them).
     #[cfg(target_os = "linux")]
-    let (user_id, group_id) =
-        if let Ok(status_content) = std::fs::read_to_string(format!("/proc/{pid}/status")) {
-            let mut uid = 0u32;
-            let mut gid = 0u32;
-
-            for line in status_content.lines() {
-                if let Some(value) = line.strip_prefix("Uid:") {
-                    // Uid line format: "Uid:	1000	1000	1000	1000" (real, effective, saved, filesystem)
-                    // We want the real UID (first value)
-                    if let Some(uid_str) = value.split_whitespace().next() {
-                        uid = uid_str.parse().unwrap_or(0);
-                    }
-                } else if let Some(value) = line.strip_prefix("Gid:") {
-                    // Gid line format: "Gid:	1000	1000	1000	1000" (real, effective, saved, filesystem)
-                    // We want the real GID (first value)
-                    if let Some(gid_str) = value.split_whitespace().next() {
-                        gid = gid_str.parse().unwrap_or(0);
-                    }
-                }
-            }
-
-            (uid, gid)
-        } else {
-            // Fallback if /proc read fails (permission issue)
-            (0, 0)
-        };
+    let (user_id, group_id) = read_proc_status(pid)
+        .map(|s| (s.uid, s.gid))
+        .unwrap_or((0, 0));
 
     #[cfg(not(target_os = "linux"))]
     let (user_id, group_id) = (0, 0);
@@ -1248,6 +1349,9 @@ pub async fn collect_process_metrics(
     // Collect thread information (Linux only)
     let threads = collect_thread_info(pid);
 
+    // One read of /proc/{pid}/stat covers both user + system CPU times.
+    let (cpu_time_user, cpu_time_system) = get_cpu_times_ms(pid);
+
     // Now construct the detailed info without holding the lock
     let detailed_info = DetailedProcessInfo {
         pid,
@@ -1264,8 +1368,8 @@ pub async fn collect_process_metrics(
         user_id,
         group_id,
         start_time,
-        cpu_time_user: get_cpu_time_user(pid),
-        cpu_time_system: get_cpu_time_system(pid),
+        cpu_time_user,
+        cpu_time_system,
         read_bytes,
         write_bytes,
         working_directory,

socktop_agent/src/state.rs

@@ -17,6 +17,10 @@ pub type SharedNetworks = Arc<Mutex<Networks>>;
 pub struct ProcCpuTracker {
     pub last_total: u64,
     pub last_per_pid: HashMap<u32, u64>,
+    /// PID → process name cache. Mirrors the non-Linux `ProcessCache.names`.
+    /// On a Pi with ~150-300 mostly-stable processes this avoids re-allocating
+    /// the same `String`s on every processes poll (~once per 1.5s).
+    pub names: HashMap<u32, String>,
 }
 
 #[cfg(not(target_os = "linux"))]

socktop_agent/src/ws.rs

@@ -69,12 +69,12 @@ async fn handle_socket(mut socket: WebSocket, state: AppState) {
             Message::Text(ref text) if text == "get_processes" => {
                 let payload = collect_processes_all(&state).await;
 
-                // Map to protobuf message
-                // Get cached buffers
+                // Get cached buffers. The Vec capacity is preserved across
+                // calls (with_capacity(512) seeds it, then we swap-back after
+                // encode so the allocation outlives any single request).
                 let cache = COMPRESSION_CACHE.get_or_init(|| Mutex::new(CompressionCache::new()));
                 let mut cache = cache.lock().await;
 
-                // Reuse process vector to build the list
                 cache.processes_vec.clear();
                 cache
                     .processes_vec
@@ -85,29 +85,38 @@ async fn handle_socket(mut socket: WebSocket, state: AppState) {
                         mem_bytes: p.mem_bytes,
                     }));
 
-                let pb = pb::Processes {
+                // Move the populated Vec into the proto, encode, then move it
+                // BACK into the cache so the next call reuses the same heap
+                // allocation. The previous code did `mem::take(...)` here but
+                // then dropped `pb` (and the Vec along with it), leaving the
+                // cache holding an empty zero-capacity Vec — defeating the
+                // whole point of `with_capacity(512)`.
+                let mut pb = pb::Processes {
                     process_count: payload.process_count as u64,
                     rows: std::mem::take(&mut cache.processes_vec),
                 };
 
                 let mut buf = Vec::with_capacity(8 * 1024);
-                if prost::Message::encode(&pb, &mut buf).is_err() {
+                let encode_result = prost::Message::encode(&pb, &mut buf);
+                // Restore the (now-encoded-from) Vec to the cache before pb is
+                // dropped. We `take` it out of pb to leave that field empty,
+                // and the next request will `.clear()` before refilling.
+                cache.processes_vec = std::mem::take(&mut pb.rows);
+
+                if encode_result.is_err() {
                     let _ = socket.send(Message::Close(None)).await;
+                } else if buf.len() <= COMPRESSION_THRESHOLD {
+                    let _ = socket.send(Message::Binary(buf)).await;
                 } else {
-                    // compress if large
-                    if buf.len() <= COMPRESSION_THRESHOLD {
-                        let _ = socket.send(Message::Binary(buf)).await;
-                    } else {
-                        // Create a new encoder for each message to ensure proper gzip headers
-                        let mut encoder =
-                            GzEncoder::new(Vec::with_capacity(buf.len()), Compression::fast());
-                        match encoder.write_all(&buf).and_then(|_| encoder.finish()) {
-                            Ok(compressed) => {
-                                let _ = socket.send(Message::Binary(compressed)).await;
-                            }
-                            Err(_) => {
-                                let _ = socket.send(Message::Binary(buf)).await;
-                            }
+                    // Create a new encoder for each message to ensure proper gzip headers
+                    let mut encoder =
+                        GzEncoder::new(Vec::with_capacity(buf.len()), Compression::fast());
+                    match encoder.write_all(&buf).and_then(|_| encoder.finish()) {
+                        Ok(compressed) => {
+                            let _ = socket.send(Message::Binary(compressed)).await;
+                        }
+                        Err(_) => {
+                            let _ = socket.send(Message::Binary(buf)).await;
                         }
                     }
                 }

socktop_wasm_test/Cargo.lock

@@ -37,9 +37,9 @@ checksum = "46c5e41b57b8bba42a04676d81cb89e9ee8e859a1a66f80a5a72e1cb76b34d43"
 
 [[package]]
 name = "bytes"
-version = "1.10.1"
+version = "1.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d71b6127be86fdcfddb610f7182ac57211d4b18a3e9c82eb2d17662f2227ad6a"
+checksum = "1e748733b7cbc798e1434b6ac524f0c1ff2ab456fe201501e6497c8417a4fc33"
 
 [[package]]
 name = "cfg-if"