So what's faster about Firefox 3.0? To find out, I ran Firefox 2.0, Firefox 2.0.1.4, Firefox 3.0 and Safari 3.1.1 through a battery of objective tests. I used the SunSpider JavaScript Benchmark, which showed me that Firefox 3 bests today's Safari by a small amount of time.

The big news, though, is that Firefox 3 processes JavaScript more than three times faster than Firefox 2. I also ran tests loading 10 multiple tabs simultaneously and other page-load tests. Firefox 3 edged out its predecessors and Safari 3.1.1 by a small margin in those tests. On paper, it's the currently fastest.

There is one downside to Firefox 3, however. The first time you launch it after starting up OS X, Firefox 3 takes 5.5 seconds to open a blank page. By contrast, Safari 3.1.1 takes about half a second for the same task. It's a noticeable difference. If you're the kind of person whose Mac is always running, though, it's a moot point.

Firefox has also had perennial stability issues, sometimes leading to loss of performance over time, as a result of memory leaks. To be honest, though, I've only ever seen or heard about that problem under Windows. Mozilla's developers were able to rid the Gecko 1.9 browser engine—under development for almost three years—of some of the reliability-robbing inefficiencies of its predecessors. According to Mozilla's Firefox release notes:

Memory usage: Several new technologies work together to reduce the amount of memory used by Firefox 3 over a Web browsing session. Memory cycles are broken and collected by an automated cycle collector, a new memory allocator reduces fragmentation, hundreds of leaks have been fixed, and caching strategies have been tuned.

And then there are the intangibles: I have always liked the way Firefox feels. What does that mean? I can't really explain it. Safari doesn't have the fun factor that I get from Firefox. Safari may take you down the virtual highway with performance akin to a BMW M3, but while you're doing it, you'll feel like you're driving your father's Oldsmobile. (Is there any other kind anymore?) Firefox feels more like the M3, and now it comes close in the speed department. Of course, Apple has reportedly released a beta of Safari 4 to its developer community, so there's another chapter to come.