Very nice and performant. What's the secret?
Number two is that, even though it's running a physics simulation for each animation, we kept the physics code really simple. The simulation code generally takes less time than the drawing itself.
It also doesn't rely on jquery animate, which has a lot of extra cruft to run on older browsers and support legacy code. Writing the rendering in pure javascript helps a ton.
And I think the last thing is that, when the animations respond with the velocity of your interaction it makes everything feel really smooth.
Even if an animation runs at 60fps, if the way it responds to your touch feels bad, the animation won't look good.
Quick question for anyone passing by: Do the latest versions of jQuery still have this issue? I know 2.x dropped legacy support, so it would be interesting to see how much efficiency with things like animations has increased.
Right now it's iOS and Android, and works on most versions I've been able to test on. It works on windows tablet, but I haven't been able to get my hands on a windows phone.
Also, it works on all modern desktop browsers, IE 10+, with IE 9 support coming soon.
The home page title I can flick around, and it reacts to velocity and direction, but if I try and drag it, it lets go before I get very far and goes back to its default state.
Similarly the pull-down menu on the home page - I can pull it down, but it goes at its own speed - I can't drag it or give it velocity.
On the demos page - I can't scroll the page, so can only get to chat heads. This one, like the home page title, I can flick around with velocity and direction, but can't keep hold of it. And the background image moves too.
Windows Phone 8.0.10328.78, Nokia Lumia 520 (480x800)
(PS. In iOS, personally I'd find it easier if the demos opened in the same page so the back button works.)