OK. I can't actually call it "Firefox" due to trademark concerns, but a colleague sent me this link to "Minefield," which is a version of Firefox optimized for the Mac.
Is it any good? Well, according to one user, "Starts up faster, scrolls smoother, resizes windows smoother...It's like it's Safari." In other words, a bit like the new launcher icons for OpenOffice.org Aqua, but probably better.
Does this mean it will? (Mind you, the gap wasn't very wide.) Perhaps.
I'm going to download it now and give it a try. It
won't will work with Firefox extensions so it doesn't hold much interest for me (What would I do without Adblock Plus, Forecast Fox, and my other Firefox extensions?), so it's a great way to get both the best of performance and the best of third-party extensions. For those of you looking for a Mac-optimized speed demon, this may well be your day.
Updated with correct information on extensions. Thanks, James, for the correction.