I've heard that IE9+ has very effective GPU rendering. That could explain its rendering and animation/scrolling performance. The GPU compositor in Chrome & Safari is kinda hacked-in; it renders layers on the CPU first, blits them to the GPU as a texture, and then composits on a full-layer basis. Touch the CPU renderer and performance immediately goes to shit.

I wouldn't be surprised if things get better, at least for Chrome, in the near future.