Unfortunately the game was taken down due to the Japan situation. Understandable.
Under Safari i was able to simulate ~80 live physics objects in a high collision environment at full frame render, bound to the DOM at 60fps on reasonable hardware 6 months ago (safari still has the fastest DOM paint time out there now).
Even when using Firefox 3.6 i could manage around 20 dynamic objects.
No CSS3 animation, just math and re-paints.
Javascript Math is not slow (at all), its generally the DOM/Canvas slowing you down.
I'm really impressed with what JS can do these days...
Seriously, I'm having way too much fun swinging this ball around and smashing things. Package it up for $0.99 IMO.