Thank you guys!
I think the reason it runs smooth on ios is because I kept it really simple.
I only do collision checks every 0.1 seconds and I don't have many sprites on the canvas.
I exported to cocoonjs with webGl checked.
It is some lag on iphone 4 though.
I have made an update to the game on app store. Added a replay button, I will do the same on the kongregate version.
If you do play the game, please rate it. I only have about 30 downloads per day on app store...