fix: resolve critical performance issues and UI hangs by optimizing polling and PSS collection

src/App.tsx

@@ -91,8 +91,8 @@ function App() {
   const [history, setHistory] = useState<{ time: string; cpu: number }[]>([]);
   const [report, setReport] = useState<ProfilingReport | null>(null);
 
+  // Initial report check
   useEffect(() => {
-    // Check for initial report (from CLI args)
     const checkInitialReport = async () => {
         try {
             const data = await invoke<ProfilingReport | null>('get_initial_report');
@@ -105,13 +105,23 @@ function App() {
         }
     };
     checkInitialReport();
+  }, []);
+
+  // Stats Polling
+  useEffect(() => {
+    let timeoutId: number;
+    let isMounted = true;
 
     const fetchStats = async () => {
+      if (view !== 'dashboard' && !stats?.is_recording) return;
+      
       try {
-        const isRecording = stats?.is_recording ?? false;
         const data = await invoke<SystemStats>('get_system_stats', { 
-            minimal: isRecording || view === 'report' 
+            minimal: (stats?.is_recording || view === 'report') 
         });
+        
+        if (!isMounted) return;
+
         setStats(data);
         
         const avgCpu = data.cpu_usage.reduce((a, b) => a + b, 0) / data.cpu_usage.length;
@@ -123,12 +133,18 @@ function App() {
         });
       } catch (e) {
         console.error(e);
+      } finally {
+        if (isMounted) {
+            timeoutId = window.setTimeout(fetchStats, 1000);
+        }
       }
     };
 
     fetchStats();
-    const interval = setInterval(fetchStats, 1000);
-    return () => clearInterval(interval);
+    return () => {
+        isMounted = false;
+        clearTimeout(timeoutId);
+    };
   }, [view, stats?.is_recording]);
 
   const toggleRecording = async () => {