Did you mean, "alpha" instead of "beta"? Because AFAIK, there is no Firefox 7 beta released as of now. Neither I could find it here, and nor my Aurora got updated to beta. Its Firefox 7 alpha 1 as of now.
On browser benchmarks:
I have said it before as well. I just wonder when people starts talking about page load difference in milliseconds / microseconds. Do you really notice that difference? Do you? Really? :S
+1. But i can notice sluggishness of IE9 and FF when multiple sites are loading and i switch between tabs at that time. FF is still OK, but IE9 is pure crap.