After opening several tabs/windows and then closing them, Firefox does not "give back" used RAM and slows considerably when holding the memory.




9 years ago
4 months ago


(Reporter: Jeff Dorfman, Unassigned)


3.0 Branch
Mac OS X

Firefox Tracking Flags

(Not tracked)



(1 attachment)



9 years ago
User-Agent:       Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv: Gecko/2008070206 Firefox/3.0.1
Build Identifier: Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv: Gecko/2008070206 Firefox/3.0.1

After opening several tab/windoes, firefox keeps a substantial amount of ram (up to 1MB for 15-20 open tabs/windows), and then keeps that as windows are closed. When Firefox takes most of the RAM available, all activities slow substantially -- sometimes 1 minute to switch between windows. It is not possible to close some windows, continue to use others and then open new windows.

Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv: Gecko/2008070206 Firefox/3.0.1

PowerBook G4 1.33Ghz 1.25MB RAM (max) 6S 10.4.11

Reproducible: Always

Steps to Reproduce:
1. Open several windows/tabs -- 15-20 total.
2. Use all, then close some or all of them.
3. Opening and closing windows over time also appears to induce an accumulation of used memory that is not released.
Actual Results:  
RAM held by Firefox interferes with its own running as you continue, necessitating restarting firefox and/or restarting OS.

The software should release the RAM it is no longer using and make it available for opening new windows and/or running other applications. In its current form, Firefox slows down substantially and it or the machine must be restarted.


9 years ago
Version: unspecified → 3.0 Branch

Comment 1

9 years ago
I assume you have more than 1.25 MB of RAM or your computer would likely not work running any modern Operating System.

Please read more about Firefox memory usage here:

Comment 2

9 years ago
Sorry 1.25GB

Comment 3

9 years ago
Previous description of Firefox keeping 1MB should read keeping 1GB.
Thank you.

Comment 4

9 years ago
Well it really depends on what is going on in those 15-20 tabs. 1 GB is unusual but not necessarily Firefox's fault, it could be ill-programed plug-ins, large movie files etc.. And memory is not gained because it's not as simple as just giving up the memory, firstly because of how OS memory management works and secondly because keeping the cache is useful for when people click "undo close tab".

However there are settings you can change which you may find useful:

Comment 5

9 years ago
Thank you for your help.

Comment 6

9 years ago
results with FF 3.1 beta and started in safe mode?

Comment 7

7 years ago
no response to question, so => incomplete
Last Resolved: 7 years ago
Resolution: --- → INCOMPLETE

Comment 8

8 months ago
Windows 7x64, 42.0.1

I have use FF without restart at some days, opened and closed websites. As result 13 tabs is opened and 8400 MB RAM+ROM is eaten.

Steps to reproduce (better use saved session):
1. Open session with 100 tabs
2. Renew all
2.1 Check memory usage
3. Close half of them
3.1 check memort usage

Good result: FF eats less memory
Bad result: FF eats memory without changes

Comment 9

4 months ago
Created attachment 8876543 [details]

The using of memory has increased harshly until hour and a half, only one new tab has been opened:
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