I'm pretty sure opera has had this for a while.

I can't tell if you're being sarcastic or not. (Why the downvotes? It's an honest question. Firefox has stagnated and is falling behind in features and performance. Simple but major UX frustrations like this seem bewildering when I load up Firefox for a casual surf instead of Chrome.)

Far from it. I think it's great that they don't simply forget problems from 10 years ago, but that they're able to return to and fix them. It'd be better if they didn't take 10 years to do so, but then again, I'm not complaining, either.

it's not sarcasm

It should be. Every other browser gets this problem correct and has. My other comment here is more verbose, but Firefox has become something of a monolithic joke. Every time I fire it up, I'm truly hopeful that it will have improved. Then 30 seconds later when it has finally opened, I see the same tired Firefox2/3.x interface and slow page rendering on top of the (well, now fixed) modal problems, etc.

It's nice to see that the JS speedups have some effect, but it's still behind Chrome technically. (though there do seem to be a (very, imo) few Firefox extensions that don't have Chrome equivalents, so I do understand).

I say this every time someone comments with very slow Fx startups, and I know this isn’t the elegant way to fix the problem, but 30 secs to start a browser is broken behaviour. Have you tried creating a new Firefox profile?

http://support.mozilla.com/en-US/kb/Managing+profiles

hehe, It's a fresh install of Firefox 4. It clears my cache, cookies, history, etc on close. No extensions, personas, or themes. It's as clean as it gets, and it is still that broken.

30 seconds is an exaggeration but it's easily 5 times as slow as Chrome is to start up.

To me, Firefox (4) with Panorama is the best UI a browser's ever had.