I use Firefox for most of my web surfing as I've got it dialed in just the way I want it. It's fast and has add-on features that I really like.
But recently I found a web page with tips on tuning IE7 for faster performance. I did the tweaks on my IE7 and by golly they weren't kidding. It's noticeably faster than the stock version.
In fact, I'm now using IE7 more than Firefox. Try it, you might like it.