For me, (nVidia GTX 980) Chrome beats Firefox on Windows 8.1 by a lot when rendering 300,000 bunnies.
- Chrome 44: 100 FPS
- Firefox 40: 60 FPS
- IE 11: 10 FPS
I don't think that FF is limiting itself to 60 FPS as I have a 144Hz monitor and other WebGL demos can render at frame rates well in excess of 60 FPS in firefox.