dashboard: pause polling when tab is hidden

static/dashboard.js

@@ -662,5 +662,37 @@ function fetchStats() {
         .catch(function(e) { $('dot').className = 'dot err'; $('statusTxt').textContent = 'Error'; });
 }
 
-fetchStats();
-setInterval(fetchStats, 3000);
+// Visibility-aware polling - pause when tab is hidden
+var pollInterval = null;
+var pollDelay = 3000;
+
+function startPolling() {
+    if (!pollInterval) {
+        fetchStats();  // Fetch immediately
+        pollInterval = setInterval(fetchStats, pollDelay);
+    }
+}
+
+function stopPolling() {
+    if (pollInterval) {
+        clearInterval(pollInterval);
+        pollInterval = null;
+        $('dot').className = 'dot warn';
+        $('statusTxt').textContent = 'Paused';
+    }
+}
+
+function handleVisibilityChange() {
+    if (document.hidden) {
+        stopPolling();
+    } else {
+        startPolling();
+    }
+}
+
+document.addEventListener('visibilitychange', handleVisibilityChange);
+
+// Initial start
+if (!document.hidden) {
+    startPolling();
+}