TheDev ( and for ludei)
I'm in the same situation. Used to do tests with CocoonJs, whith wonderful results, all things seems to run at 55-60fps.
Started to build a simple physics game, and have no success with performance testing. Done all the performance tips (reduced physics and non-physics objects number by 50%), made the Screen smaller (zoom-in) to show less object in screen in a time, removed all text objects, etc...
The best I can achieve were about 27-32FPS what sounds to be good, but is really horrible to play, cause of the very slow moton of physics.
I used to think that 20-60 physics objects are OK for a mobile (1,2Ghz CPU + GPU) with CocoonJS wrapper, but I can not optimize my game to make it. :(
I can provide a capx/CocoonExport for ludei if they can look at this project to discover which functions make it dead on mobile.