[s-macke]

Don't know. But here some possibilities:

1. No fullscreen

2. I update the screen only if a key is pressed.(No rain, that has to be rendered all the time)

3. I don't use any costly canvas functions. I render everything myself in a pixelbuffer.

4. Typed arrays

[hunterloftis]

It's #2. Redrawing at 60hz (or as close as the machine can come) is what hits the cpu so hard.

[s-macke]

No, I don't use requestAnimationFrame right now. I think when I wrote it, it was not supported by IE. But can't remember.

I calculate as close as the machine can but with a window.setTimeout(Update, 0); in order to be responsive.