IMHO a lot has to do with what you're trying to accomplish -- one of the browsers based off the big 3 has multiple engines to speed display in some instances. Then there are the 64 bit variants, which might be faster in some situations. And the page you're trying to view has something to do with it, as 1 browser may be better/faster with HTML 5 for example.
Personally I've got nothing for or against Chrome, but on this rig I don't see any real difference or advantage compared to Firefox, so I've just stuck with that, which I set to remove all history, cookies etc. on exit. On the old laptop project [an OLD win98 machine I upgraded to XP] I found Chrome wants to use much more RAM than Firefox, while ie8 wants/needs too much processing horsepower. If I recall correctly Opera was OK, but didn't work quite as well as Firefox.