Swiftfox is optimized Firefox. It comes with many editions for your CPU. I downloaded it for my Athlon 64X2 box. It is loading and surfing very fast. I recommend all of you to use it.
My Firefox was left behind on the panel without touching since then.
Updated on 2007-06-21 :
I installed Fasterfox addon as advised by huygens-25. It is running smooth and fast. It also blocked the popup flash in some websites. A real good stuff.