Firefox 54.0.1 eats memory like a pig

Since FF hit the v. 54, it gobbles up memory like there's no tomorrow. The way I used to browse internet before was perfectly fine for older versions (lots of tabs, etc.), but since I updated, I've had FF nearly crash my machine countless times. And I write 'nearly' because I was barely able to kill it via tty2 by the skin of my teeth, but to any non-techie user, the machine looks simply simply brain-dead. Infuriatingly, most of the time, when you feel FF becomes sluggish, closing it triggers another round of mallocs (why? BUT WHY?) that seals the fate of what little free ram you had left, throwing the whole thing on its knees.
When this happens, and there's no free ram left, the load of the machine instantly shoot past 20, and I've seen a peak in top nearing 50 (!!!) ; meanwhile, it doesn't look like FF is swapping, or just a little (500 MB, maybe 1GB, for a ram of 8GB and a swap partition of the same size).
To be sure, I removed FF-KDE and installed vanilla FF, but to no avail. Same problem.
Currently, I consider FF to be unusable. This doesn't please me, because FF has long been a healthy competitor to IE and Chrome, and without it, it might very well have been game over free internet a long time ago.
I don't know if there are ways to keep FF within reasonable borders to avoid locking up the machine, but anyway there are fundamental problems to troubleshoot here.


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How much memory does your system have and how much of that memory is firefox "eating"? How long does it take during normal usage for these issues to occur?

How many tabs do you usually have open simultaneously? How many addons and / or themes do you run? Does the same thing happen with new profiles? FF 54 is multiprocess by default, could be a rogue addon memory leaking?

I run both firefox kde and waterfox kde in firejail with a lot of different addons, memory footprint remains pretty constant during usage.


FF eats whatever it can and reaches 100% ram consumption, on multiple systems, most are 4GB, main desktop 8GB. Time is irrelevant, it depends on the number of opened/closed tabs, and the 'weight' of each tab. It looks like memory is never given back to the system. Usually I have 10+ tabs open at any given time, no themes beside default, and adblock + Flash Video Downloader extension. It happens with old and new profiles alike. I don't think it's a leak per se, more like a grab and hold.

Thx for your interest,

not having your problem because i stuck with 52 esr, but you could limit how much physicial memory it can take with cgroups. that may not be worth setting up if it's just a bug that will be fixed in 55, though.

Just launched waterfox kde, starting memory usage was around 450MB, opened between 40 and 50 new tabs, memory usage jumped to more than 1GB, closed all the tabs and it only dropped to around 900MB, so could be an issue. Does FF cache anything in memory?

Just closed the browser whilst watching total mem usage it looks like all the FF memory is being reclaimed successfully by the kernel.

I was having the same issue as you with firefox ( normal firefox ) a few days ( months?) ago. I was quite frustrated with it, as it keeps freezing even when I'm not using other programs

But now. Suddenly I'm surprised now that my firefox runs very fine, even while I'm playing a game ...

I'm not sure why this is happening but I think this is happen because of either :

I hope my input help your issues!


Firefox is normally not the problem. Extensions are normally the problem.

Start with a clean profile (or in Safe Mode, firefox -safe-mode) and see if the issue occurs. If not, it's an extension you have installed.


I agree with jonathon, extensions can make a real difference. There's a special extension for Firefox that checks the other extensions for compatibilty with FF and Electrolysis or how that thing is called.

My KDE system with firefox-kde with three normal open tabs takes about 1 GB total, it keeps this 1 GB until I close firefox, closing a tab doesn't liberate the memory.

@thefallenrat, I see no difference at all regarding firefox between 4.9 and 4.12 regardless of IO schedulers, WMs or DEs (I use i3 with compton and KDE - the former feels snappier due to the fact that compton is superior to kwin compositor on my system). I've tested this only yesterday...
What exactly has changed for you?

I'm not sure either, but I said it anyway because that's what I did recently and it may have connections with it ( Oh! I forgot to mention that I used compton too!)

What I noticed lately is that , playing video in youtube feels snappier now, opening 4 tabs while playing a game and also opening clementine, hexchat and liferea didn't freeze my system...

Right now I'm typing this while playing steam game

Thanks, that's interesting. I'm going to check it again. But I can't play games, the old Core2Duo is too slow for that...
I believe the IO scheduler could play a role in that with your heavy multitasking.

@mauve02, maybe you can watch the continuous output of meminfo with watch -n 1 cat /proc/meminfo and see how this evolves when you're actively using firefox.

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about:performance in firefox address bar shows a breakdown of RAM usage. Might not solve your problem, but it's another tool you can use to see where your memory goes.


Thank you everyone for all the tips. I'm still investigating this. Meanwhile, if you want to replicate my issue (if this does impact you), just open 4~5 Bing. com images search pages and do some large generic searches, clicking on images at random. You should see memory consumption rocketing sky-high, and worse, not really getting entirely down when closing the tabs.
I tried to monitor extensions etc., but I have no real solution yet.


So you're saying this happens with a clean profile? If so it's quite possibly a bug and needs to be reported upstream.

If you haven't tried with a clean profile, please do so. Otherwise everyone is just wasting their time.

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From this page,34792.html

Switching to a simpler extension model allows Firefox to enable multiple processes and also isolate them in sandboxes.

The more sandboxed the content is, the less sharing happens between multiple tabs. With a rise in the number of used browser tabs, the memory usage also increases significantly, as “redundant” code is added to each process and sandbox.


From what the previous posts say, this sounds like a memory leak to me best to report it.

Well it seems to be adblock related. I have adblock installed with the package manager, and when I swaped it in favour of ublock origin, there were still high peaks of memory consumption, but the memory blocks were released some time after the tab's closing. Still too much to my taste, still allocating gobs of memory upon closing tabs (released later on now), but better.
Thx everyone,


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Yes ram has gone up significantly before this release it was never really noticable to me i'm modest with tabs and look at security different open tab open door is how I see it. ram used to go from 450mb - to 800 now its 1200mb one tab on my low ram gnome3 setup and about the same on KDE

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So memory issues were, in fact, due to an extension.

You really should disable your other extensions to find out which others are badly behaved.

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Thanks, didn't know about this one!

Thanks, didn't know about this one!

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