OS X & Firefox 1.5
If you’re using Firefox on a Mac, you really need to upgrade to 1.5 right away. It’s gotten a spring back in step, most notable on page loads, switching tabs, etc.
(On the downside, I can no longer use about half the Firefox extensions I’ve installed, as they’re not updated for 1.5 yet, but c’est la vie’.)

November 30th, 2005 at 8:51 am
But what about the fact that ctrl-tab won’t cycle between open tabs? And the fact that Fx1.5 for OS X randomly loses keyboard focus when closing a tab?
I really like the speed improvements, and the built-in stuff like tag rearranging and automatic cache cleaning, but I really can’t stand using it in its current state. I’m a keyboard junkie, and my most-used features for mouseless browsing are all broken.