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.
The long list of new features in Firefox 3.0 is attractive in its own right. For example, there's a selection of welcome security tweaks, full-page zoom, better password management, a new download manager, and numerous improvements to address-bar auto-complete and bookmarks. New Mac integration includes a native OS X application look and feel, support for OS X widgets and support of some Growl notifications -- although the "green + button" still does a Windows-style maximize.
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.
The catch: Bookmark synching
Despite the newfound performance and pleasant interface, I'm not necessarily dropping Safari like a hot potato in favour of Firefox. Apple has another ace up its sleeve with respect to Safari -- especially for people like me who live and work on multiple Macs. Apple's .Mac service (recently renamed MobileMe or .Me for short) can automatically synchronize browser bookmarks, usernames and passwords on all your Macs. This Apple service costs $99 a year, so it's not for everyone. But for those who do use it, it's another reason to stick with Safari.
I'm unaware of similar service for Firefox that works as seamlessly and automatically as MobileMe. There are several utilities and services that you can use to solve the problem. For example, you can get around the problem by using a Web-based service, like Google Bookmarks. (I'm not as fond as many people are of using Google and Yahoo for personal data like email, so it's not a method I'd prefer.)
I've recently come across two products that look promising: Foxmarks Bookmark Synchronizer (free) and Everyday Software's BookIt ($12). Neither of these products has the whole ball of wax. Foxmarks appears to handle everything I want it to, but only among Firefox browsers (including Firefox 3). BookIt is a manual synching tool (it doesn't work automatically), but it works with multiple browsers and even supports the iPhone (although in its current 3.75 release, BookIt does not support Firefox 3).
Firefox has caught up to Safari's performance but has not surpassed it in any notable way. What that means is that the decision is effectively a photo finish for the legions of Safari users on the Mac. It will probably come down to individual perceptions and predilections. As a previous Firefox user and supporter and also someone who has been using Safari for the better part of two years, I've got skin in the game on both sides of the question. It's going to take me some time to sort it out.
The question for me -- the decision point -- after I install Firefox 3 on one of my machines is: "Should I make Firefox my default browser?" So far, except for the purposes of testing, Safari is still winning. But that may just be muscle memory.
One thing is for sure: This is one Firefox upgrade that existing Firefox users don't want to miss. And whatever browser you use on your Mac, you'll want to check out Firefox 3. It's that good.