That's odd. Like I said, I had 100 entities onscreen @ 20fps no problem. Granted they weren't all moving very fast....hmmmm....60 might not be a unrealistic high end.

Here's how we can do this:
Finish the level...tweak it out real nice with all sorts of non-physics bells and whistles....don't do a lick of physics....send me your level balls included...I'LL tweak your physics settings and see if I can't get a few extra balls/fps.