Chrome is the slowest (even with hardware acceleration turned on via command line switches), Opera competes very well up to a point, but at the end just Firefox and Internet Explorer are the winners with 1000 fish swimming around.
Both Firefox and IE9 use Direct2D to utilize the GPU's rendering power -- so it's probably no surprise that they both show very similar results. It's most apparent when comparing CPU use; IE9 and FF3.7 are both miles ahead in performance, but both show the lowest CPU utilization!
This is just an experiment from the Download squad, but this can give us the idea on what to wait on the near future with the release of FF, IE, Chrome and Opera and of course the main attraction HTML5.
Source: Download Squad