The only reason this demo uses a lot of CPU is because it uses a lot of tricks to stay under 1K. Any JS guy could get the same result with far less CPU usage. Also, HTML5 has nothing to do with CPU usage. JavaScript performance (which is quite a bit better than Flash, even with SVG and/or Canvas manipulations) is the thing that actually uses CPU.
It's no help that JS is faster than AS for now, AS used to be much faster than contemporary JS, but how about display ads with dozens of Flash embedded? Fast is only relative.
Think about dozens of canvas animation ads embedded with Javascript. It will be as shitty as Flash. I'll switch to the first browser that allows me to selectively disable all HTML5 crap.
