According to Ludei, it should be very close. Are you having problems?
Here is my story so far.
I contacted Ludei few weeks ago because I have been testing my game with iPhone 4 and CocoonJS 1.4 with poor results (10-15 fps) - my game was unplayable on older devices.
I removed big tiled backgrounds (smaller still work) and turned off the WebGL support and now it plays 25-45 fps. Not great, but it is playable again.
Another improvement could be made by activating the texture reducer.
They also said that they will release a new version of CocoonJS with a new audio system soon that might improve the performance!
Hope this helps.