Firefox 4 has released a video that shows ants running around:
So I ran it on my MacBook 2.4GHz Core 2 Duo on each of my browsers:
- Firefox 3.6.12 = 40 fps - drops to 12 over time
- Firefox 4b7 = 80 fps - stays fairly constant > 70 fps
- Safari 5 = 90 fps - stays fairly constant > 85 fps
- Chrome 7 = 110 fps - moves between 100 and 140 fps
Now I don't know the validity of this test as a basis of real speed comparison, but if one was to take those numbers as is, it shows that Firefox 4 is the slowest of the new browsers.
I am making no judgement at this stage, just printing the numbers I found.