3D cube lags on firefox

Hello all! it's a while ;P
I'm actually working on a Rubik's Cube simulator with stencyl; all is good but it lags incredibly when i play it on Stencyl Arcade with Firefox.
http://www.stencyl.com/game/play/26399

if I try it with Chrome, it works perfectly. It works even on Firefox if the swf is loaded on another website.
Can anyone help me about this hellish lag?
Thanks!

I'm seeing the same problem with Lava Bird in FireFox. It works fine in Safari and Chrome, but in FF the "shockwave flash" plugin takes up 80% of the cpu.