diff --git a/js/simulation.js b/js/simulation.js
index 463a5af..abaeffb 100644
--- a/js/simulation.js
+++ b/js/simulation.js
@@ -1,20 +1,31 @@
-// Clock simulation engine
+// Clock simulation engine — uses real timestamps for consistent timing
 import { state } from './state.js';
 import { evaluateAll } from './gates.js';
 import { forceRecordSample } from './waveform.js';
 
-export function simTick() {
-    // Toggle all CLOCK gates
-    state.gates.forEach(g => {
-        if (g.type === 'CLOCK') {
-            g.value = g.value ? 0 : 1;
+let lastTickTime = 0;
+let animFrameId = null;
+
+function simLoop(now) {
+    if (!state.simRunning) return;
+
+    // Fire ticks that are due based on real elapsed time
+    while (now - lastTickTime >= state.simSpeed) {
+        lastTickTime += state.simSpeed;
+
+        // Toggle all CLOCK gates
+        state.gates.forEach(g => {
+            if (g.type === 'CLOCK') {
+                g.value = g.value ? 0 : 1;
+            }
+        });
+        evaluateAll();
+        if (state.recording && state.waveformVisible) {
+            forceRecordSample();
         }
-    });
-    evaluateAll();
-    // Force record even if evaluateAll didn't detect change
-    if (state.recording && state.waveformVisible) {
-        forceRecordSample();
     }
+
+    animFrameId = requestAnimationFrame(simLoop);
 }
 
 export function startSim() {
@@ -29,18 +40,18 @@ export function startSim() {
         state.waveformVisible = true;
         document.getElementById('waveform-panel').classList.add('visible');
         document.getElementById('sim-btn').classList.add('active');
-        // Trigger resize via event so renderer picks it up
         window.dispatchEvent(new Event('resize'));
     }
 
-    state.simInterval = setInterval(simTick, state.simSpeed);
+    lastTickTime = performance.now();
+    animFrameId = requestAnimationFrame(simLoop);
     updateSimUI();
 }
 
 export function stopSim() {
     state.simRunning = false;
-    if (state.simInterval) clearInterval(state.simInterval);
-    state.simInterval = null;
+    if (animFrameId) cancelAnimationFrame(animFrameId);
+    animFrameId = null;
     updateSimUI();
 }
 
@@ -57,10 +68,8 @@ export function updateSimUI() {
 }
 
 export function adjustSpeed(delta) {
+    const wasRunning = state.simRunning;
     state.simSpeed = Math.max(50, Math.min(2000, state.simSpeed + delta));
-    if (state.simRunning) {
-        clearInterval(state.simInterval);
-        state.simInterval = setInterval(simTick, state.simSpeed);
-    }
+    // No need to restart — the loop reads simSpeed dynamically
     updateSimUI();
 }