My good friend Hatham El-Fadeel pointed me to a post that states how good is the performance of the latest beta of Firefox 3 is compared to other web browsers and to even the previous beta of Firefox 3.
I though to jump right in and take the same test using my laptop as a test bed. An HP dv2775ee Core 2 Duo 2.5GHz 6MB Cache (T9300) with 4GB RAM on a Vista Home Premium 64 Bit
WOW!! The Firefox team is doing magical stuff to their engine leaving both Opera and IE teams with some serious competition....the closest match is IE8 and it's 2x slower!!
Update: Coding horror has covered this a long time ago, in a much detailed way.