I like the irony of this being #7: FastestFox - Browse Faster: 31% slower...

Stumbleupon's 11th, wtf is that doing at startup?

Stumbling about aimlessly, of course!

Firebug is well worth it, in my opinion. I installed FF4 recently and was happy to notice that Firebug was a lot faster. Unfortunately, either FF4 or Firebug is leaking memory like crazy. I'm talking 800MB in 20 minutes with only two tabs open debugging a simple local application. I had to go back to FF3.6. Hopefully they'll fix that soon.

Mozilla developer here - If you have steps to reproduce, I'd love to hear them and I'll get them forwarded to the proper people.

Well, I can tell you that I only had the latest FF4 and Firebug installed (this was 3 days ago). No other add-ons were installed.

The only other change was to disable the video acceleration because I was getting some weird flashes on page reloads. My home page (Google.com) was flashing for a few milliseconds while reloading my local app. From what I remember, disabling the hardware acceleration fixed that issue.

Other than this it was basically make changes to my local site, hit refresh in FF, make changes, refresh again, and so on. Nothing special about this site, basic HTML / CSS / Javascript (jQuery), no Flash. You could see the memory steadily go up in the Task Manager.

The only reason I even noticed it was because the whole system was slowing down. I only have 3GB of RAM (Windows 7 64 bit), but I never noticed any memory pressures before. I could "feel" Windows paging the memory to disk which was slowing down everything on the box.

Good luck, and let me know if there's something else I could do to help.

The memory problem is pretty serious. I've been using the Memory Restart addon (https://addons.mozilla.org/en-us/firefox/addon/memory-restar...), which shows memory use in the bottom corner and lets you click to restart when it goes over a certain amount.

Wow. I leave FF open for weeks with many tabs on a netbook with 1GB of memory.

hmmm... I have to reboot daily - sometimes more than once a day - on an ASUS Eee 1GB running XP

If I leave Firefox open during the day the memory goes up to 1.2 GB. The performance slows down at about 800BM memory. I have 8 GB so it's not a big deal but it still seems an awful lot of memory.

I found this to be pretty surprising as well. It also made me wonder what Firefox feels like with no addons installed. I pretty much automatically add my 'essential' addons whenever dealing with a clean version of Firefox and this list includes 2 of the top 10 slow performers (Firebug and Xmarks). Now I kind of want to strip it down to bare FF just to get a good baseline.

I have firebug and other development related addons in their own profile because of this.

My regular browsing is done in the default profile and the development work is done with the development profile.

I knew it! :-). Run it with ExtJS and you'll start to go crazy.

I wish that list wouldn't be about a metric I couldn't care less about but unfortunately everyone else seems to only care about start up time :(