After testing, Memory Fox does not help Firefox's memory usage/leaks. What it does is clear out the "working set" memory that the Firefox process uses. The Working Set is the memory kept resident in physical memory for use by the process. I can watch in Process Explorer and see as the Working Set memory for Firefox drops from some-odd hundreds of megabytes to very low values like 24MB. However, Firefox's Private Bytes total--the memory reserved exclusively for the process remains unaffected.

Actually that's not true. During some operations, the private bytes for Firefox go up tremendously, sometimes nearly doubling the total from values like ~550MB to over a gigabyte. It then reverts back to its steady-state 550MB after a short time. I expect this is because the system has to load up the pages that formerly used to be kept around in the Working Set into active memory to be used. These pages then get dumped by Memory Fox after a short while.

This push-pull of Firefox and Memory Fox ends up slowing down Firefox even worse than without Memory Fox at all. For example, creating a new window takes seconds to load, and there is a huge memory spike in the Private Bytes total. Not only that, there is a huge CPU spike for the process as the system needs to drag in memory that was previously cached, but was flushed by Memory Fox. As for the original problems with Firefox slowdowns and periodic stuttering, they do not go away. Baseline memory usage (Private Bytes) in Firefox does not go down, and is unaffected by Memory Fox except with memory spikes as data needs to be read in. Closing browser windows, as before, do not release allocated memory.

Verdict: Do no use Memory Fox. Memory Fox is not only useless, but detrimental to Firefox usage. The add-on may sometimes save memory, but when performing operations, the program spikes memory far worse than if Memory Fox were not present. Whatmore, it appears Memory Fox interferes with Windows' caching and memory management, causing slowdowns. The memory leaks in Firefox can only be remedied by Mozilla, as they are internal.

Yes it has an extreme leak whenever you use Flash, and no, separating the plugin container hasn't solved the issue.

To demonstrate:

Open Process Manager

Open Youtube in multiple tabs, say four or five.

Play the movies.

Close all tabs.

Note Memory usage before and after.

Vimeo is even worse.

This seems to be a problem with EVERY version after 3.1 and now that I am running 3.6.12 it is OH so much fun to see my browser CRASH MANY times a day and blame the new Plugin-Container. REALLY, I am almost tempted to be unsecured and back on IE just so I can browse the web again without my browser crashing. Come on guys! and why is it that it seems like the browser LOVES to run at 50%CPU time and hit over a gig REALLY quickly with 12 tabs open...and then watch to see the plugin container jump up as to as high as 80% of that....thats 2gigs GONE, a slower computer AND one really pissed off client!

@Bionic-Badger. Private bytes in Process Explorer corresponds to the amount of virtual memory being used, not the total amount of VM + Physical RAM.

One thing I noticed about the memory leak associated with firefox is that updated your JRE to the most recent build resolved my issue with the memory leak. If you haven't tried this, I would recommend it.

Hmm, so if you want to use firefox, use it without (some of) what makes it better than other browsers (add-ons and plugins). Common Sense Rating of 0/10. Common sense solution: use another browser, since using the stuff that makes Fx cool screws it up anyway. Fanboys/girls will howl, but they're fanboys anyway, who listens? You can wait for an update that maybe will fix the issue, or you can get off this tub and look for a better boat.

I've been experiencing the same thing using firefox in Windows 7 x64 bit and on Ubuntu Linux x64 bit... Huge memory leak, typing slows to a crawl, all other browsers seem to be fine. I thought it was google toolbar at first, I removed it, same problem, removed greasemonkey, still persists. I think it's just Firefox.

I had to switch to Google Chrome and Google Chromium, both seem to handle tabs without using 1.5 gigs of ram. (running on a laptop with 8 gigs, quad core)

Now that they make Firebug for Chrome, I really don't need firefox, I hope they fix it though, it used to be my #1 browser. :(

Upgrade to version 3.6.14 (or later or version 4.x). Version 3.6.14 (just released last night) fixes two memory leaks, one of which was first reported in 2007 (affecting 3.0, 3.5 and 3.6)! Why it has taken nearly 4 years to fix I don't know, but I strongly suspect it is the reason for >300 crashes on my 5 PCs alone over the past few years! Basically if you had a tab open on one of Microsoft's techie pages, it would leak memory. If you left your browser open overnight or at the weekend, you would come back to see it had crashed or disappeared. I don't know whether Microsoft were intentially exploiting this memory leak to cause Firefox users problems so they switched to using Internet Explorer, or whether it is a genuine bug in their javascript code that caused it to exploit this memory leak, but either way, it was convenient for them! ;) Here is one of the bug reports.

Anyway, thanks guys for fixing the leak! (Eventually!)

If this reply fixed your problem, please mark this as helpful!

I've never had any problems with memory leaks after using about:config for browser memory capacity and changing my privacy settings when closing FF for every single version of FF including the current one. I've been an FF user for years and will continue to do so. Also, I always make it a habit to close my browser when I sign off from my computer.

@carbonfiberhoods.com

Try the about:config to change your browser memory capacity in FF. I don't think it's Firefox that's the issue. Also check how much memory you're using for your paging on your computer.

I have had these problems with Firefox since I started using more than 3 tabs which was at least 6 years ago and have never seen an improvement. I use it on all Windows OS and with or without plugins, it still leaks memory. I now usually have about 10-50 tabs open and have the minimize hack to clear out memory but it gets really annoying having to minimize and maximize everytime just for it to run properly. As for plugins, I have about 10 running and I thought these are tested properly by Mozilla's team for issues and compatibility but I'm not sure on this.

Anyways, my biggest problems is flash and shockwave in firefox and some javascripts as well. For the past 10 days, youtube.com is displaying really slow and video is like loading one image at a time, however I can watch youtube videos fine on facebook and other sites. Will do a research on this too.

I guess I can't ask for a perfect software since it is free but I will still use it because it is better than others at the moment. Chrome still not great and plugins aren't there yet and don't get me started on IE.. The other browsers just always seem 2 years behind at least. I'm a web designer/developer and I got used to using firefox as my main tool but would love this crashing/memory leak issues to be fixed.

Same here. Windows 7 64bit, 4gb ram. I usually run 3-4 windows with 10-20 tabs each. FF starts at 400mb, and becomes unusable at around 1.8gb, when it gets "stuck" periodically, about once or twice per minute, for a couple of seconds. Very irritating.

I tried disabling addons, it did help a bit, but didn't solve the problem.

The leaks became much worse since the version 4 beta's (been using them since #8 I think).

Today I decided to try and run a single window with few tabs. FF started at 200mb, and reached 1.8gb after ~12 hours of work (web development). I monitored its memory all along, it doesn't seem to ever deallocate memory. Memory consumption goes up a bit for every page displayed, and never goes down.

After having those issues for years now, I decided that enough is enough. I'm trying to solve this one last time, if it doesn't work out I'm ditching FF for Chrome. Too bad Mozilla prefers catching up with other browser's features (e.g. 3D acceleration) instead of maturing and stabilizing the core browser features.

This bug is annoying enough to get me to sign up just to report that it is most definitely NOT fixed as of the latest 3.6 version (3.6.16).

Firefox continues to accumulate memory usage and never releases it until the program is completely shut down. For folks who like to leave their web-based email open in a browser window all day, this means that by the end of the day (if you have enough RAM available so that it hasn't already become unstable and crashed on you due to running out of memory to allocate) it will be using well over 1GB of RAM just from normal usage including YouTube viewing throughout the day.

As I write this, I've been using Firefox for about two hours, and currently have three tabs open - one GMail, one for this thread, and one for a Youtube video I'm in the midst of watching. Firefox is currently sucking up 405MB of RAM, mostly due to previous sites I'd visited over the past two hours but have since closed their tabs (or reused one to surf to this page for example). Ridiculous.

Please figure out how to make your browser function properly and release Private Working Set memory when a tab or non-primary window is closed.

Thanks.

Win7 x64, 8GB of RAM. Firefox crashes out when it starts sucking over 1.2GB - 1.5/1.8GB. When it reloads itself with the same windows/tabs open, it's using a tiny fraction of the memory it was hogging just before the crash.

Workaround found: Open about:blank in one tab and the memory leak is gone. If memory istill grows refresh about:blank to free memory.

hi, i have exactly same problem. Firefox crashes when memory usage is ~1.3GB. Anyone knows what the solution is?

I just reacquired this problem after upgrading to FF 4.0.1 So I do have a solution to this problem for version 3.6.x since only one add-on failed to upgrade to 4.0.1.

Install BarTab 2.0 add-on. Bar Tab stops any tabs from taking CPU slices while they do not have the focus thus halting their memory creep. Now that I've lost BarTab I came back to my machine which had the same session of about 23 tabs from version 3.6.14 that would sit open for 5 or 7 days straight and after 24 hours has claimed 750MB of my 2GB RAM and is unresponsive and had to be killed with process explorer or task manager.

I can tell you that the other add-on's I had installed that I had hoped would solve the problem were AdBlock Plus, NoScript, FlashBlock, Better Privacy but with only these running these same set of 23 tabs are not under proper memory management. I would however always recommend a script blocker, ad blocker, flash blocker, flash cookie blocker and a web page analyzer like WOT (NOT McAfee Site Adviser which has been helping Saudi Arabia spy on it's populace.)

• SO the solution for this problem on version prior to 4.x is Bar Tab add-on. *

(My credentials are computer repair tech from 1989 till 1998 and since my duties have been anti virus, anti malware repair and data recovery services)

(I've been using FireFox since version 0.9 and mostly have seen it abbreviated as FF not Fx... Fx is a video card series and an abbreviation for effects like sound Fx, special Fx and so we never used Fx to avoid problems in tech support communications).

I have a second fix I use for this problem. It is an overall workaround to any bad-apps that won't clean up their RAM usage.

There is a little set of utilities that are fairly powerful and must be used carefully. In this set of utilities is one called simply "MemoryCleaner" and it is part of "Reg Toy" utilities by a clever programmer named Kì Nam I think from Viet Nam.

The Clear Memory utility rests on the taskbar and has an option to 'Trim Processes Working Set". You can watch the Task Manager showing FF with 888 MB RAM claimed and then select this Clear Memory option and watch FF RAM reduce to 17kb and then it slowly reclaims only what it needs.

• Warning!!! Sometimes this step does cause some apps to crash. Notably Safari for Windows with Flash windows open. Oddly, if you refuse to acknowledge the Safari crash dialog and drag it off screen Safari for Windows keeps working. I haven't noticed any other apps crash after reclaiming working set but it might happen. Still... being able to clear FF RAM and other apps RAM and causing the machine to go from stalled and lagging to instantly usable is so sweet!!!

• Reg Toy can be found on download.com.

• Another Warning! Reg Toy is a powerful tweaking programming and should not be used lightly. I do not think many of it's uses will work on Windows 7 and I believe he has moved onto other projects.

• Be Careful out there!!! Have WOT or Avast, A-Squared, ESET or some other anti-malware software running for sites that are close to the download.com spelling (like a before o) or other popular download sites exist to catch the unwary typist and will install malware on a machine without real-time protection.

• I have sent an email to the Reg Toy dev to contact these forums.

Hi, sorry to shout, but I think this "weird" memory issue concerns EVERY MOZILLA (GECKO) BROWSER TO DATE. I noticed not only Firefox 1.x/2.x/3.x/4.x is eating up memory (even with only 1 - literally ONE - page loaded, but being refreshed continuosly), but also SeaMonkey 1.x/2.x. I did reproduce this "bug" also in Conkeror, and K-Meleon (both use Gecko).

What I did is this. 1. I opened up ie. http://www.nk.pl (it's a Polish social portal most Poles use these days). I logged in, checked the memory usage of the browser application process. It is usually around 80-120mb after only loading this one page alone for the first time. The nk.pl has a lot of dynamic content, MOSTLY graphics (people post a lot of pictures there). This could be a clue of some sort. 2. Then I started refreshing the page by pressing F5. Sadly, I noticed that after every page refresh the browser memory usage increased about 10-15MB.

The worse part is not only the memory usage went up, but the browser application interface became more laggy in response to user's input and in overall behavior.

After hitting F5 for about 20 or so times, another refresh would take several seconds to finish, and even a 1-2 seconds to actually start refreshing. The memory usage grows to 200-300MB, which I find literally sickening, because what I have here is only 1 tab open and in this tab I did not even clicked 1 stinking link. I am only refreshing the page.

The responsivness of the browser dropps down dramatically to the point the application becomes totally unusable - in the end it stops responding to the input for such long time you could consider it froze completely. The only remedy to this is to kill the processes, which then takes another couple of seconds, sometimes even a minute.

I do this on a fresh install of all the aformentioned browsers. No addons, no additional plugins except for adobe flash (10.3) and java (6u25). I have Windows XP SP3 32-bit, but I can reproduce this on WinVista/7 and even on Ubuntu 10.10/11.04.

Note. It is not happenning on every page in the Internet. I am aware of that. I suspect dynamic content or heavy graphics are the initiator/catalisyst.

Ok, I experience this annoyance for longer than 2 years now, when I actually started using Firefox/Mozilla as my main browser. I tried every possible configuration tweak you can find on the net, so here I beg, for f* sake, don't tell me to use safe mode or disable my antivirus software or any of this sh* because it only pisses me even more. I don't have the antivirus enebled anyway, and secondly, I do not even consider running a web browser in a safe mode. It is ridiculous to thing, an ordinary user should ever do this. And frankly, I don't have any more time for this, as it seems like fighting with windmills.

Also, the problem doesn't seem to occur when using the latest Opera browser. At least I did not noticed it til now. I won't say anything about IE, because I got rid of this spyware long ago.

In conclusion...

I don't think this "memory leak", as it's called, is a problem of Firefox or Seamonkey or any Gecko browser, or even Flash or Java. I strongly suspect the Gecko itself could be to blame or maybe JS engine. I do not know exactly, for I am not an expert here.

I will continue to monitor Firefox/SeaMonkey/K-Meleon/Conkeror behavior, and see, if there is some improvements in the future. I suggest testing all Gecko-based browsers and see if you can reproduce the leakage in anything other than Firefox.

Cheers, fox21

PS. Please, forgive my bad English. I am still learning it =)

This is a Firefox core issue, not some add-on. While there are many add-ons that can cause memory leaks, the real problem is for those users who have generally 5+ tabs opened on their browser. Left alone, these 5+ tabs will begin to accumulate memory usage of upwards 3GB depending on your system, and number of tabs, and what websites you are looking at (for example, flash websites).

No amount of disabling add-ons fixes this particular problem, though it might help for some people who have massive amounts of add-ons (10+, or specific ones). The reason why other browsers have risen in usage, IE9 and Chrome, is largely linked to the fact that Firefox has failed to address this issue over the years. To be fair however, I've noticed Chrome also uses up a large amount of memory, but does not increase in size during inactivity over a long period of time like Firefox. IE9 does not seem to exhibit this behavior.

Having this problem too. Really annoying. It persists since version 3.x and is still present in 4.01. I made a screenshot with vmmap open.

Screenshot with vmmap

It seems FF is allocating exactly one 1MB chunk for every website you visited since whenever and never releases them. If, as mentioned above, FF keeps 8 pages back in memory, for every site one has visited and possibly even executing active content in them, this could be a reasonably simple explanation, in particular if one has TabMixPlus installed itself keeping more than 10 pages in the "Recently closed tabs"-List...

I suspected a memory leak, but this rises the probable explanation of a seriously flawed memory caching algorithm, because having all those pages in memory wouldn't slow down FF that much. Every site (with active content?) in cache must be "executed" - explaining the tremendous slowdown over the time.

Eliminating this "feature" would speed up FF more than any other optimization, I guess...

At least a step closer to a solution.