It's still laggy on older phones, and even on my Galaxy S5 it has its slight jitter every once in a while. Still trying to optimize, and of course export for iOS. HTML5 still seems limited for any fast-paced action game. My next project will be less dependent on any jitters that could happen in the game.
Minimize the amount of collision checks, images (large ones especially), sift through events and see if you can organize them more efficiently, reduce the number of "run every tick" style events.