Sisyphus Could you trace your steps so I know what you've tried?
I tried changing almost every function separately, to see if magically it works. That didn't help.
I tried disabling webgl, NO.
I tried lowering text quantity (FPS increased, but just by a little. still 200+ words lag awfully)
Well, i didn't do anything, i just replace all spritefonts to a sprites with text's when noticed the fps lowering
UPD: I just try to open a project with 2 sprite fonts with random text 1000x3000 in mobile browser, and fps is still 60! In cocoonjs launcher i have only 15fps with that project. So i think it's a problem in cocoonjs, try to report it to ludei.