diff --git a/app/components/NDS3D.vue b/app/components/NDS3D.vue
index 85030d4..c2fb190 100644
--- a/app/components/NDS3D.vue
+++ b/app/components/NDS3D.vue
@@ -200,9 +200,10 @@ watch(
 const { onRender, onBeforeRender } = useLoop();
 
 const LAG_FPS_THRESHOLD = 40;
-const LAG_DURATION_SECS = 1;
+const LAG_DURATION_SECS = 5;
 let lagSeconds = 0;
 let lagCheckDone = false;
+let lastFrameTime = Date.now();
 
 const HINT_SPRITE_SCALE = 2;
 const HINT_SPRITE_DPR = 4;
@@ -345,8 +346,17 @@ useKeyUp(({ ndsButton }) => {
 });
 
 // lag detection
-onBeforeRender(({ delta }) => {
+onBeforeRender(() => {
   if (!lagCheckDone) {
+    const now = Date.now();
+    const delta = (now - lastFrameTime) / 1000;
+    lastFrameTime = now;
+
+    if (document.hidden || delta > 0.5) {
+      lagSeconds = 0;
+      return;
+    }
+
     const fps = 1 / delta;
     if (fps < LAG_FPS_THRESHOLD) {
       lagSeconds += delta;