Frame Rate drops with animation

Hi guys, i have a weird problem in my game(on the web-mobile version).
whenever i try to play more than two animations, with different nodes at the same time(using the play on load option or via code) my framerate drops to 4 for a little bit of time.
This same problem doesn’t occur on the windows release or the android.
I am using Mozilla Firefox, but the issue remains on Google Chrome!

Can someone help me?

P.S: I created the game using Cocos Creator 1.5.0