diff --git a/CHANGELOG.md b/CHANGELOG.md
index 44de37c7..b939f9b4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -162,6 +162,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 
 
+### Performance Probe — thread-group CPU toggle
+
+**By [@cucadmuh](https://github.com/cucadmuh), PR [#891](https://github.com/Psychotoxical/psysonic/pull/891)**
+
+* Monitor live poll: explicit opt-in checkbox for Linux `/proc` thread-group CPU (off by default); fixes camelCase IPC so thread rows populate instead of staying on “Collecting…”.
+
+
+
 ## Changed
 
 ### Linux — session GDK, WebKitGTK mitigations, and Wayland text
diff --git a/src-tauri/src/lib_commands/app_api/perf.rs b/src-tauri/src/lib_commands/app_api/perf.rs
index 115e470f..df8ba34e 100644
--- a/src-tauri/src/lib_commands/app_api/perf.rs
+++ b/src-tauri/src/lib_commands/app_api/perf.rs
@@ -11,6 +11,7 @@ use std::sync::Mutex;
 #[cfg(target_os = "linux")]
 use std::fs;
 
+#[cfg(any(target_os = "linux", target_os = "macos"))]
 const CHILD_RESCAN_EVERY: u8 = 8;
 
 #[derive(Debug, Clone, Serialize)]
diff --git a/src/components/sidebar/perfProbe/PerfLivePollControls.tsx b/src/components/sidebar/perfProbe/PerfLivePollControls.tsx
index 3fbedf6f..39df88b1 100644
--- a/src/components/sidebar/perfProbe/PerfLivePollControls.tsx
+++ b/src/components/sidebar/perfProbe/PerfLivePollControls.tsx
@@ -2,12 +2,15 @@ import {
   PERF_LIVE_POLL_MS_MAX,
   PERF_LIVE_POLL_MS_MIN,
   PERF_LIVE_POLL_MS_STEP,
+  setPerfLiveIncludeThreadGroups,
   setPerfLivePollIntervalMs,
+  usePerfLiveIncludeThreadGroups,
   usePerfLivePollIntervalMs,
 } from '../../../utils/perf/perfLivePollSettings';
 
 export default function PerfLivePollControls() {
   const pollMs = usePerfLivePollIntervalMs();
+  const includeThreadGroups = usePerfLiveIncludeThreadGroups();
   const pollSec = (pollMs / 1000).toFixed(1);
 
   return (
@@ -28,6 +31,19 @@ export default function PerfLivePollControls() {
           onChange={e => setPerfLivePollIntervalMs(Number(e.target.value))}
         />
       </label>
+      <label className="perf-live-poll__row perf-live-poll__row--check">
+        <input
+          type="checkbox"
+          checked={includeThreadGroups}
+          onChange={e => setPerfLiveIncludeThreadGroups(e.target.checked)}
+        />
+        <span className="perf-live-poll__check-label">
+          CPU by psysonic threads
+        </span>
+      </label>
+      <p className="perf-live-poll__hint">
+        Scans in-process thread groups each poll (Linux). Off by default — enable only while diagnosing.
+      </p>
     </section>
   );
 }
diff --git a/src/components/sidebar/perfProbe/SidebarPerfProbeMonitorTab.tsx b/src/components/sidebar/perfProbe/SidebarPerfProbeMonitorTab.tsx
index ae900572..d0153fb6 100644
--- a/src/components/sidebar/perfProbe/SidebarPerfProbeMonitorTab.tsx
+++ b/src/components/sidebar/perfProbe/SidebarPerfProbeMonitorTab.tsx
@@ -1,8 +1,6 @@
-import { useEffect, useMemo, useRef, useState } from 'react';
+import { useMemo, useRef } from 'react';
 import { usePerfLiveSnapshot } from '../../../utils/perf/perfLiveStore';
-import {
-  syncPerfLiveThreadGroupsNeed,
-} from '../../../utils/perf/perfLivePollSettings';
+import { usePerfLiveIncludeThreadGroups } from '../../../utils/perf/perfLivePollSettings';
 import {
   togglePerfLiveOverlayPin,
   togglePipelineOverlayPin,
@@ -28,13 +26,9 @@ export default function SidebarPerfProbeMonitorTab() {
   const coverPinned = usePipelineOverlayPinned('pipeline:cover');
   const cpu = live.cpu;
   const collecting = live.collecting && cpu == null;
+  const includeThreadGroups = usePerfLiveIncludeThreadGroups();
   const peakMemoryKbRef = useRef(1);
   const peakThreadCpuRef = useRef(1);
-  const [threadSectionOpen, setThreadSectionOpen] = useState(false);
-
-  useEffect(() => {
-    syncPerfLiveThreadGroupsNeed(threadSectionOpen, livePins);
-  }, [threadSectionOpen, livePins]);
 
   const maxMemoryKb = useMemo(() => {
     const current = Math.max(1, ...(cpu?.memory.map(m => m.rss_kb) ?? [1]));
@@ -123,11 +117,10 @@ export default function SidebarPerfProbeMonitorTab() {
             />
           </PerfProbeMetricSection>
 
-          {(cpu.threadCpu.length > 0 || threadSectionOpen) && (
+          {includeThreadGroups && (
             <PerfProbeMetricSection
               title="CPU — psysonic threads"
-              defaultOpen={false}
-              onOpenChange={setThreadSectionOpen}
+              defaultOpen
             >
               {cpu.threadCpu.length > 0 ? cpu.threadCpu.map(row => {
                 const pinId = `cpu:thread:${row.label}` as PerfLiveOverlayPinId;
@@ -145,7 +138,9 @@ export default function SidebarPerfProbeMonitorTab() {
                   />
                 );
               }) : (
-                <div className="perf-monitor-empty perf-monitor-empty--inline">Collecting thread samples…</div>
+                <div className="perf-monitor-empty perf-monitor-empty--inline">
+                  No named psysonic threads yet — wait for the next poll or load audio/analysis work.
+                </div>
               )}
             </PerfProbeMetricSection>
           )}
diff --git a/src/config/settingsCredits.ts b/src/config/settingsCredits.ts
index a242d6d3..2f9f3e3e 100644
--- a/src/config/settingsCredits.ts
+++ b/src/config/settingsCredits.ts
@@ -341,6 +341,7 @@ const CONTRIBUTOR_ENTRIES = [
       'Discord Rich Presence: configurable activity-name template — member list shows the playing track instead of "Psysonic" (PR #885)',
       'Library browse: lazy 200-row local catalog chunks, unified in-page scroll, cover priority during scroll (PR #890)',
       'Performance Probe: Monitor/Toggles redesign, live CPU/RSS/thread metrics, overlay pins and sparklines, macOS snapshots (PR #890)',
+      'Performance Probe: opt-in thread-group CPU poll toggle and includeThreadGroups IPC fix (PR #891)',
     ],
   },
   {
diff --git a/src/hooks/useSidebarPerfProbe.ts b/src/hooks/useSidebarPerfProbe.ts
index 185f3c7c..20fd278f 100644
--- a/src/hooks/useSidebarPerfProbe.ts
+++ b/src/hooks/useSidebarPerfProbe.ts
@@ -8,7 +8,6 @@ import {
   subscribePerfProbeFlags,
 } from '../utils/perf/perfFlags';
 import { hasAnyLiveMetricPollNeed, usePerfLiveOverlayPins } from '../utils/perf/perfOverlayPins';
-import { syncPerfLiveThreadGroupsNeed } from '../utils/perf/perfLivePollSettings';
 import { useSyncExternalStore } from 'react';
 
 interface Result {
@@ -41,11 +40,6 @@ export function useSidebarPerfProbe(): Result {
 
   useAnalysisPerfListener(needAnalysis);
 
-  useEffect(() => {
-    if (perfProbeOpen) return;
-    syncPerfLiveThreadGroupsNeed(false, livePins);
-  }, [perfProbeOpen, livePins]);
-
   useEffect(() => {
     setPerfProbeTelemetryActive(perfProbeOpen);
     return () => setPerfProbeTelemetryActive(false);
diff --git a/src/styles/components/modal.css b/src/styles/components/modal.css
index 7c439019..3bf7d7d6 100644
--- a/src/styles/components/modal.css
+++ b/src/styles/components/modal.css
@@ -192,6 +192,27 @@
   width: 100%;
 }
 
+.perf-live-poll__row--check {
+  flex-direction: row;
+  align-items: center;
+  gap: 8px;
+  margin-top: 10px;
+  cursor: pointer;
+  user-select: none;
+}
+
+.perf-live-poll__check-label {
+  font-size: 11px;
+  color: var(--text-primary);
+}
+
+.perf-live-poll__hint {
+  margin: 6px 0 0;
+  font-size: 10px;
+  line-height: 1.35;
+  color: color-mix(in srgb, var(--text-muted) 88%, transparent);
+}
+
 .perf-metric-section {
   margin-bottom: 10px;
   border: 1px solid color-mix(in srgb, var(--text-muted) 18%, transparent);
diff --git a/src/utils/perf/perfLivePollSettings.ts b/src/utils/perf/perfLivePollSettings.ts
index c369d011..e1f519d4 100644
--- a/src/utils/perf/perfLivePollSettings.ts
+++ b/src/utils/perf/perfLivePollSettings.ts
@@ -6,8 +6,10 @@ export const PERF_LIVE_POLL_MS_MAX = 10_000;
 export const PERF_LIVE_POLL_MS_STEP = 500;
 
 const STORAGE_KEY = 'psysonic_perf_live_poll_ms_v1';
+const THREAD_GROUPS_STORAGE_KEY = 'psysonic_perf_live_thread_groups_v1';
 
 const listeners = new Set<() => void>();
+const threadGroupListeners = new Set<() => void>();
 let pollIntervalMs = PERF_LIVE_POLL_MS_DEFAULT;
 let includeThreadGroups = false;
 let scheduleBump: (() => void) | null = null;
@@ -37,7 +39,23 @@ function initPollInterval(): void {
   }
 }
 
+function initThreadGroups(): void {
+  if (typeof window === 'undefined') return;
+  try {
+    const raw = window.localStorage.getItem(THREAD_GROUPS_STORAGE_KEY);
+    if (raw == null) return;
+    includeThreadGroups = raw === '1' || raw === 'true';
+  } catch {
+    /* ignore */
+  }
+}
+
 initPollInterval();
+initThreadGroups();
+
+function emitThreadGroups(): void {
+  threadGroupListeners.forEach(fn => fn());
+}
 
 export function getPerfLivePollIntervalMs(): number {
   return pollIntervalMs;
@@ -78,22 +96,34 @@ export function getPerfLiveIncludeThreadGroups(): boolean {
 export function setPerfLiveIncludeThreadGroups(next: boolean): void {
   if (next === includeThreadGroups) return;
   includeThreadGroups = next;
+  if (typeof window !== 'undefined') {
+    try {
+      window.localStorage.setItem(THREAD_GROUPS_STORAGE_KEY, next ? '1' : '0');
+    } catch {
+      /* ignore */
+    }
+  }
+  emitThreadGroups();
   requestScheduleBump();
 }
 
-/** Thread groups when the Monitor section is open or a thread metric is pinned. */
-export function syncPerfLiveThreadGroupsNeed(
-  sectionOpen: boolean,
-  pins: ReadonlySet<string>,
-): void {
-  const pinnedThread = [...pins].some(pin => pin.startsWith('cpu:thread:'));
-  setPerfLiveIncludeThreadGroups(sectionOpen || pinnedThread);
+export function subscribePerfLiveIncludeThreadGroups(cb: () => void): () => void {
+  threadGroupListeners.add(cb);
+  return () => threadGroupListeners.delete(cb);
+}
+
+export function usePerfLiveIncludeThreadGroups(): boolean {
+  return useSyncExternalStore(
+    subscribePerfLiveIncludeThreadGroups,
+    getPerfLiveIncludeThreadGroups,
+    () => false,
+  );
 }
 
 export type PerfCpuSnapshotRequest = {
-  include_thread_groups: boolean;
+  includeThreadGroups: boolean;
 };
 
 export function buildPerfCpuSnapshotRequest(): PerfCpuSnapshotRequest {
-  return { include_thread_groups: includeThreadGroups };
+  return { includeThreadGroups };
 }
diff --git a/src/utils/perf/perfLiveStore.ts b/src/utils/perf/perfLiveStore.ts
index 10c26244..86cc1fa6 100644
--- a/src/utils/perf/perfLiveStore.ts
+++ b/src/utils/perf/perfLiveStore.ts
@@ -231,6 +231,8 @@ export function bumpPerfLivePollSchedule(): void {
     window.clearTimeout(pollTimer);
     pollTimer = null;
   }
+  // Fresh baseline after interval / thread-group option changes.
+  prevProc = null;
   schedulePoll();
 }