I launched Firefox 4 on Friday with 4 tabs. Left work for the weekend, and came back Monday morning to Firefox using 70% of my 4.5 gigs of ram.

I'm running Ubuntu 10.10, with apt-get update; apt-get upgrade run on Friday, so it's pretty up to date.

The same for me here. I had to stop using F4 on my Mac OS Leopard. ;( To much memory used after only a few clicks.

I have the same problem and it's really frustrating ... i love Firefox, been a loyal user since day one, and it pains me to have to switch to Chrome ...

PLEASE fix this as soon as possible

OS: Snow Leopard 10.6.7 Firefox 4 only add on: Firebug but always disabled, all plugins updated and most disabled

Same problem. Even in static state, memory usage keeps slowly creeping up eventually consuming 1GB.

Mac OSX 10.6.7 with only ad-block plus add-on, updated to v 1.3.6. I too have been using Firefox for ages, but have switched to chrome until this issue is solved. I want to come back to Firefox as soon as possible!

Started Firefox in safe mode with all extensions and add-ons disabled on OS X 10.6.7 . Memory usage started at 115mb. Was up over 700mb in a short amount of time with 3 tabs running. Stayed at that level after 2 of 3 tabs closed... definite memory leak, please fix!

I currently have 8 tabs open - 4 of which are articles on Symfony, one is the Google Maps API documentation (manual page only, not an example page with a map on it), the PHP manual and two support.mozilla.com articles (including this one) - so nothing that should be resource hungry.

FF is currently using 2.81GB of memory (and it did shoot to over 3GB a moment ago when closing a tab). I've been working with a lot of JS but have now closed that tab. Firebug is very slow, as are page refreshes. The text lags as I type.

We're actively working on reducing memory leaks and memory use in Firefox. This article links to some of the technical details:

http://blog.mozilla.com/nnethercote/2011/03/10/memshrink/

Firefox 5 will be released in just a few days, and already has some improvement over Firefox 4:

http://blog.mozilla.com/nnethercote/2011/05/25/firefox-5-has-fewer-leaks-than-firefox-4/

This also depends on which add-ons and web sites you use. For example, Gmail is known to leak memory (and not just in Firefox):

http://code.google.com/p/chromium/issues/detail?id=5820

I am running on OS X 10.6.8 and get the following console message when I start up Seamonkey or Firefox:

9/13/11 12:42:01 PM seamonkey-bin[265] *** __NSAutoreleaseNoPool(): Object 0x102405c20 of class NSCFString autoreleased with no pool in place - just leaking