Hey, I've been trying to look into this a bit. Which OS (or OSes?) do you see 10-15fps on? Because so far on Mac I'm not seeing any differences compared to Chrome, but I may just be missing it...
My main OS is OS X and this is where I've done the most testing, but we see similar performance degradation on Windows as well. We've tested on multiple Macs and Windows machines. It is almost as if no hardware acceleration is being used.