diff --git a/src/audio.js b/src/audio.js
index e82b576d..fa39c7cc 100644
--- a/src/audio.js
+++ b/src/audio.js
@@ -2,8 +2,8 @@
 
 var MasterAudio = function() {
   this.master = new MasterChannel();
+  this.looper = new AudioLooper(512);
   this.start = function() {
-    this.looper = new AudioLooper(512);
     this.looper.setChannel(this.master);
     this.looper.activate();
   }
diff --git a/src/emu.js b/src/emu.js
index 28a688b1..fd62467d 100644
--- a/src/emu.js
+++ b/src/emu.js
@@ -201,7 +201,8 @@ var RAM = function(size) {
 var AnimationTimer = function(frequencyHz, callback) {
   var intervalMsec = 1000.0 / frequencyHz;
   var running;
-  var useReqAnimFrame = false; // TODO: enable?
+  var lastts = 0;
+  var useReqAnimFrame = true;
 
   function scheduleFrame() {
     if (useReqAnimFrame)
@@ -210,7 +211,14 @@ var AnimationTimer = function(frequencyHz, callback) {
       setTimeout(nextFrame, intervalMsec);
   }
   var nextFrame = function(ts) {
-    callback();
+    if (!useReqAnimFrame || ts - lastts > intervalMsec/2) {
+      if (ts - lastts < intervalMsec*30) {
+        lastts += intervalMsec;
+      } else {
+        lastts = ts;
+      }
+      callback();
+    }
     if (running) {
       scheduleFrame();
     }
@@ -221,6 +229,7 @@ var AnimationTimer = function(frequencyHz, callback) {
   this.start = function() {
     if (!running) {
       running = true;
+      lastts = 0;
       scheduleFrame();
     }
   }