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Firefox memory leak causing slow and stuttery performance

  • 32 uphendule
  • 315 zinale nkinga
  • Igcine ukuphendulwa ngu ninjawriter222

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So recently my Firefox browser has been leaking memory like crazy going up to 1.7 GB in used RAM. It starts off fine when I first open it, but progressively gets worse over time, making scrolling a choppy and painful task. This started with version 28.0 but I've since upgraded to 29.0 and the problem persisted. I've done hours of research on the problem and have tried all the following solutions, to no avail:

- Turning off hardware acceleration/smooth scrolling/auto scrolling - Creating a new profile - Completely uninstalling and reinstalling Firefox - Running it in safe mode (still lagged, even in safe mode!)

Has anyone found any real solution to this problem?

All Replies (12)

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Maybe it is a problem with the particular sites you use. Are you noticing the problem only with certain sites ?

How quickly does the memory usage rise to 2GB Within 10 minutes, 30 minutes, two hours, two days, or two weeks ?

You will be able to work out with about:memory what it is that uses all the memory.

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damn you stupid ass website lost like 2 paragraph of text....

10 tabs or more and will ram leak out to 2.8GB over 8ish hrs and crash when it wants to after not responding or it will respond again. Another thing that sucks is having FF crash while having a private window open... lost soooooo many damn tabs.

I use adblock plus and downloadhelper this started at FF 28 for me (I didnt update for a while) and has been going on ever since and is really pissing me off these days. 4gb of ram used to go alot farther with tabs, now im like cut in half.

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See, I don't really mind the high memory usage (although I'm sure others do...), but what bugs me is that Firefox becomes unusably slow once it hits 2.1 GB or so. I have 16 GB of memory to burn, and this problem shouldn't exist, but I assume it does because Firefox is a 32-bit program and can't allocate more memory. What's the long-term prognosis of this? Why is there no properly supported 64-bit version other than the debug builds?

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Hi Everyone

Please Start Your Own Thread and Cross Link it here. If you have your own issue with Firefox Memory use and stuttery performance

  • Please use this special link
    • It is faster as it cuts out a couple of steps.
    • The fellow helpers will recognise it as relating to this thread.
    1. Please remember to include your full troubleshooting information. You should see a green button that uses an addon to automate that process.
    2. If you wish post again in this thread but only to confirm you have made a new thread. (Or found a solution to the issue !)

One Question owner per thread
The primary point of treads in this forum is to solve problems for end users not to discuss development decisions. Normally and in accordance with forum guidelines we try to keep each thread to a problem seen by one specific user. It stays simpler, is easier to follow and is more likely to get a solution that way.

Memory Issues

Obviously there are many factors that affect memory use. Some of you may be running into the same issue, some of you will see the symptoms due to a completely different cause.

There will probably not be a one size fits all solution. There may well be things affecting many of you. That could involve for instance

  • Third party software or OS issues.
  • Hardware issues e.g. 32/64 bit systems, particular graphics or CPUs

I know XP users have been having graphics related problems causing slowdowns in recent Firefox versions. I know Add Block Plus (ADP) has had issues causing memory problems with Firefox, that's potentially something approaching 20 Million users affected. I am not really following the ABP issue but it probably is not yet resolved.

32 vs 64 Bit Systems & Firefox Versions or Clones Development decisions and policy are outside the scope of this forum. I am not competent to discus the pros and cons of that anyhow.

I will quote the User Advocacy Manager's (Tyler) recent comment

That's very offtopic, but the short answer is, 64bit Firefox isn't worth it. it will happen eventually, but the amount of work isn't worth the very minor performance gains. We have bigger fish to fry.
Also, honestly, 99% of users don't care if an app is 32bit or 64bit, nor do they understand what the difference even is. From the number of times I get asked about it I don't think many technical people really understand it either. It's easy to get caught up in marketing terms "64bit is 32bits more better!!!!!" but the simple fact is that for a browser, 64bit doesn't change all that much. It will happen, but there is no rush. 

It is Windows that does not have a 64 bit Firefox Release. I will mention though that Mac users report memory issues, and currently I see occasional problems; that I have not yet been able to reproduce reliably; and I mainly use Firefox 64 bit builds (on Linux).

If you use Firefox clones or forks such as Palemoon please post in their own support fora.

Turn On Telemetry IIRC the telemetry system was introduced mainly due to the fact that a Firefox 4 memory regression went unreported, it had lots of comments and complaints but apparently no actionable bugs were reported.

Your data will help prove there is a real problem in day to day use of Firefox.

Thinking aloud. In fact it may be interesting to know what Histograms or other data stored on your own computer, when FHR & telemetry is enabled and are available to study is relevant to problems with memory and slow performance. Or for that matter whether the built in profiler will be a helpful troubleshooting tool. I will ask.

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I am having a similar problem which started 2 weeks ago when I was still running Firefox 17 - yes I always wait because I know many of my addons won't work when upgrading. Anyway I decided to upgrade and is now running Firefox 31 which did in no way help this issue and I'm pretty sure Firefox is the culprit. Why am I sure? Because recently Firefox was the only program running in my Windows 7 64bit and had climbed from the initial 25% RAM use to 40-45% even though I close the tabs after use. Firefox refuses to flush the RAM it uses to present these tabs after they are closed. If I close FF there is only maybe a 5% drop in RAM. But here is where it gets interesting. The other day FF crashed and immediately I went from 45% RAM use to my initial 25% which my PC uses on a fresh boot into windows. I only have 6GB RAM and no pagefile since I have SSDs. This crash proves that FF is the culprit and that FF retains and builds RAM use even though you close the program. I have removed Adblock plus and installed Adblock Edge instead. I don't know how to solve this issue besides removing FF altogether which I would not like since I know Chrome uses even more RAM and IE is not my kind of browser.... Please help if you have an idea

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It's getting to be a joke. Fresh install of FF, with ZERO add ons and it uses 1.5 gb of ram with one stupid tab open on google. What a joke. Mozilla never fixes anything they just blame the user, add-ons, plugins, whatever they can blame to avoid taking any responsibility for their memory leaking piece of crap browser.

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Well, eventually I moved to Blue Moon on my office computer. Already forgot about memory issues and stuttery performance - Blue Moon solved them all. I kept FF on my home computer though. It's got SSD for a system disc, enough RAM, and just runs away with all the issues without me noticing much.

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Firefox is a complete joke now. With one tab open on a fresh install with NO add ons, it uses 800mb of Ram. Ridiculous. Every developer that works on this garbage browser should be fired and blacklisted from ever working in the industry again. Complete morons.

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  1. heap-unclassified leak

memory use


2,299.40 MB (100.0%) -- explicit ├──1,767.41 MB (76.86%) ── heap-unclassified

process run time

date -Iseconds 2014-09-27T15:33:45+0200

wmic process get CreationDate,Name,PageFileUsage,PeakPageFileUsage | dos2unix | grep firefox 20140916013153.339768+120 firefox.exe 2672540 2863144

all tabs (371) except about:memory are unloaded with UnloadTab "Unload Other Tabs"

Okulungisiwe ngu john_s_peterson

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I have seen some issues with firefox occasionally not responding or crashing. Usually when that happens I find that the memory usage is around the 1.5gb+ range. I generally use several windows with 10+ tabs open each, which may exacerbate the problem by filling up the memory available.

Based on the answers to this question on stack overflow->

I'd suspect that the fact Firefox is 32-bit may be a possible cause of some crashes. The responses over there indicate that 32-bit processes within Windows are generally limited to a maximum of 2GB of memory per process.

That said, the performance issues and crashing may not be directly related to the add-ons or memory leakage, but those would definitely make the problem apparent if the above is indeed part of the issue. ---

  • Quoting the results of a measure operation on the 'about:memory' page when the browser is experiencing the stated difficulties might be helpful to someone.
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I´m using firefox 32.0.3, on windows 8.1 64bits 8gb Ram, 1 tb hd. The browser goes smooth until I access this page:

the memory goes from 230 mb to 2.800 mb in few seconds and after that, the firefox becomes a black window and crashes.

Something in the page is the trigger to the memory leak, i dont know what, but since the page is pretty simple, i think its easy for someone who have experience in programming to find out.

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If the above doesn't work, please consider that Firefox has recently been having problems with adobe flash as well. Even if you aren't watching a video currently, if you had at one point since your most resent start up of fire fox it holds onto portions of that video's or web application's memory until it shuts down. The more videos or web programs that open that use flash (adobe flash) the more memory will be used until eventually you're stacking over 5,000 mb's in your RAM. This is not the fault of any add-on's such as Java or Add Block Plus.


1) Restart Firefox

2) Youtube seems to be the biggest culprit/cause of the memory leakage (or extra storage of memory through flash player onto your RAM.) So simply switch to HTML5 format. Various ways of doing this but here are a few options.

2.1) Go to or google search it and at the bottom there should be a button that says something like, "play all videos in HTML5", your current settings should be/generally are set to use "default".

2.2) Use add-ons such as YouTube ALL HTML5. They are free to download and easy to find using google, other default search providers, or simply click on tools > add-ons to open Firefox's add-on center where you will be able to search and download for free.

2) Uninstall Flash player and/or it's add-on's/extensions so they won't function with firefox (not as recommended as many web applications use Flash. Unless you know exactly what to reroute all web applications through, just don't do it. Leave it on so you may default back to it if necessary. If you do disable it however then most websites, such as youtube, should default to another player or HTML5 format.)

3) install an add on that stops flash player. (YouTube center used to work great, but now you tube has learned how to block most of it's applications)

3.1) Install video without flash (My favorite. However, youtube comments and other services won't work unless you disable it which can be done by pressing the add on's button that can be installed next to your search bar. You may need to reload the webpage once enabled/disabled. As this is such a hassle, even though I really like this player as it's lightning fast on my computer and super High Def, the hassle of having to disable and re enable is too much a hassle for the average user.)

3.2) Another option is to install VLC youtube shortcut (VLC player, which is free to download, will be needed for this one) or other similar programs. What it does is will allow your web videos to stream directly through a program on your coumputer (such as VLC my favoite rendering program)

Please take note that I have tried dozens of solutions and I have found no others that work and that Flash is indeed the main problem. Other solutions will improve performance marginally, by about 20%, but why settle for less then 100% of your computers capacity?

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