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On my Macbook running Mac OS X 10.6.7, FF 4 leaks memory like crazy. I used to let FF 3.6 open for days if not weeks, with 30 to 40 tabs open. Now FF 4 gobbles up to 1 GB of RAM after browsing to 10/20 sites, at which point I must restart it before the system becomes unusably slow.

Once it restarted in 32 bits mode, because of a plugin (perian?) and it was much less memory-hungry in 32 bits than 64; it still isn't usable for long this way.

Can anyone confirm if is a configuration related bug, or a bug with the FF4 core on Mac?

Update 1:
I confirm that FF behaves properly when running in safe mode. Apparently it still behaves normally with AdBlock+, Gmail checker and Tree Style Tabs on. I'm now testing one extension at a time. The most probable suspects so far are GreaseMonkey and Firebug.

Update 2:
Apparently the culprit is the DownloadHelper extension. I'll come back when I've got it tested some more.

Update 3:
It looks like GreaseMonkey leaks somewhat too, but I'll have to test for a couple of days to be sure.

Update 4:
Firebug seems to be leaking, and the Gmail checker too.

Update 5:
I've now opened cases on FF and DownloadHelper bugzillas.

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Back when I used FF on OS X it would leak like crazy all the time, even throughout different major versions. Maybe that's nothing new. Have you looked into Bugzilla yet? – slhck Apr 6 '11 at 20:08
I did a quick search but unfortunately there are so many leaks on various FF versions/platforms that it's hard to find any information... I'll have another look. – wazoox Apr 6 '11 at 20:25
So far I've restarting FF in safe mode and it seems OK. That's a pity, I'm using FF precisely because of the extensions :/ – wazoox Apr 7 '11 at 10:58
Please start a case on Bugzilla. Even if it is a duplicate it will (hopefully) get triaged appropriately. Fx contributors can't work on a problem that people are discussing on sites they do not use. If it matters to you, you're welcome to offer a bounty (not an SO bounty, a real money bounty) or learn how to diagnose memory leaks. Shouting about it is wasted breath. This is not particularly aimed at you, more some of the other comments. – Rushyo Apr 9 '11 at 23:33
This question was very noisy, with multiple "general discussion" type posts and no answers, so I've cleaned up the lot. To help prevent a repeat of this, I've attempted a general tidy up and removal of some slight argumentative tone from the question as well -- if someone can provide a solid answer here then please do so, otherwise it's probably left as a bug report with the developers (which seems to have been the result so far). – DMA57361 May 3 '11 at 8:39
up vote 2 down vote accepted

Time has passed, and I may confirm safely enough that the main culprit was DownloadHelper. Advice : check your extensions one by one.

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protected by studiohack Apr 7 '11 at 15:21

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