First, if you aren’t using Firefox as your primary browser, why not? It works better than Internet Explorer, it’s free, and it’s an easy download. It works on just about any computer, including PCs, Linux and the Mac. One measure of the maturity of Firefox is that I use it on a corporate intranet where a couple of years ago it wasn’t uncommon to find occasional pages that required IE to render properly. Now that’s so rare I can’t remember the last time I encountered a page that failed to display properly using Firefox.
Anyway, if you are using Firefox on a Mac, you should know that there are versions available that are optimized for both the G4 and G5 processors. I installed the G5 Firefox version and am impressed by the noticable speedup. The fact that (almost) native widgets are used is a nice bonus and makes for a much more pleasing visual experience. Sure, if Safari supported all of the Firefox extensions and supported bookmarking of multiple tabs I’d consider using the native Mac browser, but until then I’m a confirmed Firefox user. Also, I haven’t tried the G4 Firefox version, but likely will install it before my next road trip.