Thanks! I'm better at making benchmarks than I am at making games... Something to do with my real job LOL...
I hope that Ashley is quietly looking into this but I suspect that the case is closed - just from his words to me in the bug report where he all but dismissed these findings. It's quite clear that, on my hardware (i7, 16Gb, 6Gb vram - no slouch ) that r196.2 performs worse than r195 - worse both in terms of number of physics objects that can be handled and worse in terms of the frequency of frame drops that occur when the engine is stressed. The performance hike for asm.js that's been reported has not been duplicated by anyone other than Ashley, that I'm aware of.
Some fundamental changes were recently made to the physics engine and, although there is evidence that the performance is slightly worse, I think we're just going to have to learn to live with it because the aspiration is to ultimately use only asm.js. Personally, I would rather we had a full native implementation of box2d web rather than have this effort focus on implementing 'improvements' like this.
As far as I understand it, non-physics collisions are handled differently than the normal c2-optimized collision checking.