Someone actually took all their time to do this to prove which browser truely is the fastest browser. Many browsers were tested on Windows XP, Windows Vista, and Mac OSX.
Opera came out on top for the most part, whereas Firefox actually was the worst overall.
http://www.youtube.com/watch?v=1Z5U6rTcwZ8
It turns out, Firefox basically just "Fakes it" when it comes to rendering times. Interesting if you actually will believe it and not let fake biased opinions get to cloud your judgement.
These are what the browsers are. This isn't some fake opinion. Argue it all you want.