Hello jayderyu
As I said before, I used just a cube with 9 frames and the physics behavior, that is replicated in 32 instances. Besides the cube, some sprites transparent at the edges of the screen and a background image.
It is strange that only 32 objects cause much delays. I took a look at a demo in CocoonJS launcher (Box2D) and the situation is similar, but on a much larger amount in the case of the demonstration.