I got a graphics card that's blacklisted by Firefox but I am getting between 20, and 25 FPS on Firefox with canvas2d which is about the same you would get on a mobile device.
<img src="http://i44.tinypic.com/2qali5g.jpg" border="0" />
And in Google Chrome with webgl I'm getting between 55, and 60 FPS.
<img src="http://i40.tinypic.com/w8oxlg.jpg" border="0" />
I'm not getting any noticeable lag just a 5 FPS fluctuation.