It's actually not all that complicated. Firefox 4 added mozRequestAnimationFrame...

		bzbarsky on Oct 18, 2013 \| parent \| context \| favorite \| on: Show HN: My x86 emulator written in JavaScript It's actually not all that complicated. Firefox 4 added mozRequestAnimationFrame. Firefox 23 added the unprefixed version. It's documented in the browser compatibility table at https://developer.mozilla.org/en-US/docs/Web/API/window.requ... (note that "moz" next to the 4.0).

That must have done the trick, it starts now, thank you for your help.