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FF 3.6 on Mac uses more than 1 GB of memory and does not release it

  • 7 replies
  • 114 have this problem
  • 2 views
  • Last reply by NoNamer

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When using multiple tabs the memory usage climbs to 1 GB and above after a longer period of use. For example 33 Tabs open and the browser running for a few days cause 1.3 GB of Real Mem usage. Closing and restarting the browser with exactly the same tabs will use only 420 MB. In this example about 900 MB is not properly released. This has been a recurring pattern on Mac OS X 10.6 over the past 6 months. Even with 4 GB memory this is a problem, because Firefox slows down switching to other memory intensive apps. Additionally FF uses relatively high amounts of CPU even when idle on a Quad Core 3.6 Ghz processor and takes more than 10 seconds to shut down, which seems quite slow.

The problems above seem to be similar to those experienced by others on Windows 7, but many of the suggested solutions on the other threads are either too time consuming to implement or do not work.

I much prefer FF over Chrome and do not want to change browsers over this issue. Nevertheless I have observed, that Chrome (with a similar set of extensions) frees memory properly. Some people have blamed this on Flash and Flash videos, but it seems other browsers are able to release memory more effectively. Using Chrome opening and playing many Youtube Flash videos and closing them again does not hog as much memory.

If certain extensions are known to cause problems, this should be publicized on the Mozilla Extension page. It is not practical for everybody to test extensions one by one for days on end.

I disabled many of the listed plugins, but did not see any improvements. Any suggestions or links to existing solutions would be appreciated.

This happened

Every time Firefox opened

== FF has always been a memory hog since i first used it ;-) --- (I think FF 0.9 in 2004)

When using multiple tabs the memory usage climbs to 1 GB and above after a longer period of use. For example 33 Tabs open and the browser running for a few days cause 1.3 GB of Real Mem usage. Closing and restarting the browser with exactly the same tabs will use only 420 MB. In this example about 900 MB is not properly released. This has been a recurring pattern on Mac OS X 10.6 over the past 6 months. Even with 4 GB memory this is a problem, because Firefox slows down switching to other memory intensive apps. Additionally FF uses relatively high amounts of CPU even when idle on a Quad Core 3.6 Ghz processor and takes more than 10 seconds to shut down, which seems quite slow. The problems above seem to be similar to those experienced by others on Windows 7, but many of the suggested solutions on the other threads are either too time consuming to implement or do not work. I much prefer FF over Chrome and do not want to change browsers over this issue. Nevertheless I have observed, that Chrome (with a similar set of extensions) frees memory properly. Some people have blamed this on Flash and Flash videos, but it seems other browsers are able to release memory more effectively. Using Chrome opening and playing many Youtube Flash videos and closing them again does not hog as much memory. If certain extensions are known to cause problems, this should be publicized on the Mozilla Extension page. It is not practical for everybody to test extensions one by one for days on end. I disabled many of the listed plugins, but did not see any improvements. Any suggestions or links to existing solutions would be appreciated. == This happened == Every time Firefox opened == FF has always been a memory hog since i first used it ;-) --- (I think FF 0.9 in 2004)

All Replies (7)

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Wow, 1.3gb is insane. I'm on Snow Leopard as well, and Firefox is using 240mb.

Have you read the Firefox uses too much memory or CPU resources - How to fix article and tried starting in Firefox Safe Mode?

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Thanks for the link to the High Memory Usage article. I've already followed some of the recommendations, especially this one: "Restarting Firefox - Firefox's memory usage may increase if it's left open for long periods of time. A workaround for this is to periodically restart Firefox." - not a solution, though.

'Leak Monitor' did not give any useful information, just lots of pop-ups pointing to no particular add-on.

'RAMBack' does not seem to free much additional memory on initial testing, but I'll have to observe that over the long run.

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Extensions can sometimes be the cause of problems. If the problem does not occur in Safe Mode, then you can disable your extensions one-by-one until you find out which one is causing the problem. See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

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I've been reduced to using an alternative browser since upgrading Firefox to 3.6.6 on Mac OS X 10.6.4.

'Real memory' use creeps up to over 1GB over an hour or so even when I'm not actually using Firefox. This is on a high-spec Mac Pro as well.

The problem is the same when Firefox is started in 'Safe Mode', with all extensions disabled.

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I was able to reduce my maximum memory usage somewhat to about 800 MB after applying some of the recommendations. I suspected various plugins, thus I disabled all except Java, Quicktime and Flash. I still suspect, that Flash does not release memory properly on the Mac.

I also changed the setting browser.sessionhistory.max_total_viewers to 2, which may have reduced memory usage slightly.

The recommendations in http://kb.mozillazine.org/Memory_Leak talk about saving tens of MB with some changes in settings, but I am still looking at hundreds of MBs which are not being released by Firefox even after closing all tabs except one.

FF developers need to get to the root of the problems and at least make it easier to display the memory usage of each plugin and extension. It should not be left to the users to do trial-and-error testing by eliminating plugins or extensions one-by-one.

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i have the same issues, as all of you. I am on 3.6.8, disable all plugins, even all the ones that keep stuff from loading. I have seen my FF memory usage as high as 2.3GB, are your freakin kidding me, with 4 gb of system memory, that is just retarded. This is on a mac mini (springs 2009 version). I has on many times crippled my system. I am at this point looking to switch, because I can no longer tollorate this. It make me sad, as I have been using FF since early on.

I have basically turned off all cache ability's, minus the disk cache, which I have basically crippled. When I did use plugins, I was disabling flash most all the time, (it annoys me) and almost never use it for video. Disabling them only neted me 40mb, a joke, guess I will turn them all back on. I believe that the memory usage settings should be in the preferences area, not the about:config area. I feel sorry for people who have no clue.


At least they could make the program 64 bit so it would do a better job with the memory.

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I have this same problem. I can't remember if it started with when I upgraded to Snow Leopard, or when I chose to upgrade to a different version other than 3.6 (although I think it happened with 3.6 as well). I doubt it's any addons, because most of them were disabled when I upgraded to 6, 7, 8. One of them crashed multiple times a day, so I went back to a earlier release. I'm currently using 8.0.1, and Firefox was consistently using 1.3 GB of real memory even after quitting (I usually had to force quit because it would literally minutes for it to quit, maybe never quitting- I left it for 15 minutes once... still hadn't quit). The Flash plug-in alone would sometimes use 500 MB of real memory. After almost 2 years of this I can't deal with it anymore. I love FF and have used it from the beginning...

But when I turned off every addon I have (except for Tree Style Tabs, which is possibly the only thing keeping me from fully switching), and restart FF, FF is using 730 MB of RAM (well it's still climbing 740, now) and 10-20% of CPU, while the Flash plugin is using 15% of CPU. I also noticed that once I closed Gmail, my RAM usage dropped from 1.3 GB to 850 MB. It could've been something else, but that's the main thing I can think of that I did different.

When Chrome is using only 120 GB, 0.5-2% CPU usage, has been open for days, with 3 windows and multiple tabs in each... (Chrome's Flash plugin is only using 4% CPU by the way)... something is wrong with FF. I love FF, but I've grown to hate it. And this is coming from a guy who really, really, REALLY doesn't want to switch. In fact I still use FF, but am slowly weening myself off it it. It's just not worth the slow down from RAM usage and heat from my CPU (FF often spikes to near 100% usage) anymore...