A couple of months ago, I downloaded a beta version of Firefox 3 just to look at the new ideas Mozilla was working on. My intention was to try it for a couple days, then switch back to Firefox 2. I wasn't worried about stability (it's a browser after all -- what's the worst that can happen?). But the beta wasn't compatible with lots of my favorite extensions and who wants to live without them?

As it turns out, I'm still using a prerelease version of Firefox (they're at Release Candidate 1 now) and loving it, even without my beloved add-ons. The improvements Mozilla has made to the browser, while subtle, are so helpful that I didn't want to give them up. Here are five of my favorites.

1. Much better performance

 If you've used previous versions of Firefox you've likely had this experience, perhaps frequently: you're working away, but gradually become aware that something is horribly wrong with your PC. It's sluggish and apps take forever to load. You open up Task Manager and find that Firefox is chewing up 95 percent of your CPU cycles. Once you kill the browser and start over, you're running fine again.

I can't remember the last time I've had that experience with the Firefox 3 betas. Mozilla developers borrowed some memory management tricks from the Free BSD operating system for the Windows and Linux versions of Firefox. (They say memory management on Macs already worked pretty well.) The effect is clear. The browser is much less likely to commandeer too many system resources. And Firefox's developers worked to make sure that add-ons, notorious memory thieves, don't cause problems either. They've rolled in cycle collectors that help prevent extensions from locking up RAM and not giving it back. They're also distributing tools to third-party developers that will help them build more abstemious add-ons.

2. The "Awesome Bar"

 Okay, so the official name is the Location Bar, the field where you enter URLs you want to visit. But beta testers have nicknamed it the Awesome Bar and it is, well, pretty awesome. Enter text in the Location Bar and a dropdown list appears of pages from your browsing history that include that text, not just in the URL, but in the page title or the page's tag (see #4 below). The list even includes Gmail messages that include that word in the subject line. If you've already visited a Web page, there's a good chance it's useful to you. The Location Bar lets you very quickly search that useful subset of the Web.

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