[NinjaWarrior]

Yes, from the viewpoint of a game developer, the DOM is extremely, painfully, awfully, ridiculously slow and completely useless other than static HUDs. With the DOM, we can move only hundreds of sprites at 60 fps (on the latest Core i7!). HTML5 Canvas can achieve thousands but it's also far from native (and the function of Canvas is very poor).

WebGL can gain acceptable performance in many situations, but there is still much overhead.

I suspect today's most web developers don't know the true performance of computers they are actually using.