Even though it seems native, it's not. Two things are holding back performance currently in cocoonjs v 1.3 on iOS - 1, the new version isn't out yet, which has webgl which should be faster than its current rendering method. 2, cocoonjs's JavaScript execution speed isn't as fast as safari's - I seem to recall one of my tests running at something like half the speed safari was. I don't know yet if the soon to be released 1.4 improves on this or not.