As you can see from Adrian Kingsley-Hughes' SunSpider performance graph over at ZDNet's Hardware 2.0 blog, Firefox 3 RC1 is the fastest browser in the world. Firefox 3 RC1 is pretty much identical to what's going to ship as Firefox 3 next month so these are reasonably final numbers.
Users migrating to Firefox from IE 7 are going to find that performance boost to be very noticeable at popular Web applications like Gmail where messages load about 7 times faster in Firefox 3 compared to IE7. Not only that, Firefox 3 will do it with about 1/5th the RAM usage of IE7.
Tired of poky performance at Gmail, or Google Reader or other Web applications? Get Firefox 3 for the fastest experience available.