I challenge you to try to make Firefox use more RAM than my 1.4GB record

Since its inception, Firefox has been notorious for excess RAM usage, often in the form of RAM leaks. While Mozilla claims to have fixed RAM issues in recent Firefox updates, and has done a fairly good job for the most part, it is still possible to see Firefox consuming a huge chunk of your RAM — especially if you keep the browser continually open for long periods of times and have a lot of tabs open.

I have recently gotten into the (bad) habit of not closing Firefox after a session due to not wanting to lose my research and open websites. (Yes, I know Firefox has the ability to restore sessions, natively and with add-ons.) Yesterday my computer was going extremely sluggish so I decided to take a look way. As it turns out, Firefox (v15.0.1) was consuming more than 1.4GB of memory — a massive amount, by anyone’s standards. (I probably had anywhere from 50-100 tabs open — I didn’t count.) The sad part is that isn’t even the highest I have seen it go. Prior to capturing the screenshot you see above, I actually hit over 1.5GB of Firefox RAM usage. However, I was about to start a League of Legends session and my computer was literally grinding to a halt (almost 90-95% memory usage) so I couldn’t snap a screenshot.

Can you beat my record? Sound-off in the comments below!

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  • tommaso
  • Rob (Down Under)

    . . . (Spread them into multiple portable IceDragons)
    Create Folders for multiple copies of Comodo IceDragon portable.
    (When you install IceDragon, you tick one box and it makes it portable.)
    Place (‘place’ because no install required) IceDragon into one folder, and call it IceDragon_MASK
    Run it and add NoScript and other desirable Extensions and PlugIns.
    Run it for a wee while, so that you can fine tune it (EG add Search box to the top of screen, etc).
    Now create other folders for say – Health, Hardware, Software, ETC
    Copy the contents of your mask into each of them.
    (You can run any one of them at the same time as your installed FireFox)
    You can ‘move’ Tabs from FF into those IceDragons.
    Bookmark all your tabs in FF, and then export them to HTML.
    You can open that HTML file in each IceDragon, to ‘move’ Tabs from FF

  • Glenn

    I usually sit on 4Gb, but only got 6gb ram
    and trying to uni work on high demand programs is becoming hard

  • pdecker414


    Ease to keep tabs. Use processes tab in task manager and end the task. When you launch Firefox again, all tabs will reopen. I have to do it often especially if I need to reboot my computer due to a Microsoft update.

  • RobCr

    All those guilty of keeping many Tabs open raise your hand (my hand is up).
    Beware occasions where a new window is opened (even though you have expressly forbidden that).
    If you do not notice that window and close down your main FF, then all your open Tabs get discarded. It happened to me recently.
    If anyone knows how to ensure that that can never happen, I am all ears ?

  • Ajeh

    I have 300+ tabs at a time broken into 15 tab groups and have reached about double of yours for 3,000,136k in FireFox … but then I got nervous and restarted before going any higher.

    The restart dropped me down to 665,260k.

    I usually only restart FireFox when I reboot my computer.

  • Dimitri

    Point either chrome or firefox to about:memory and they’ll divulge a verbose breakdown of where they spend your precious memory.

    Firefox isn’t so bad lately. (5 months after Ashraf’s post) Using 18.0.2, I get between 2 and 3 gigs, which I find acceptable for uptime running into months and more than 50 tabs open (400+ tabs only 50 of which are loaded at a time. Cheers, for “load page on focus” option. I have a strong affinity for Ctrl+t->googling things and leaving things open for reference).

    The problem in memory usage, at least from my usage case, seems to be FlashPlayerPlugin and plugin-container growth. Flash seems to grow easily but seldom shrinks in memory despite closing flash tabs. It has gotten better though.

    I have had no performance issues even with hundreds of live tabs. I’m not a heavy plugin user though, so that might help. Lastly, chrome is worse than Firefox in tab/memory usage, but that doesn’t make it worse in my eyes. They just work differently. I use them both, with an affinity for Firefox.

    For comparison:
    Firefox 18.0.2
    200MB fresh, between 2-3GB dirty
    between 10-100+ active tabs
    Up-time usually more than a month at a time
    16GB ram, installed on SSD

  • After leaving it open 2 days doing usual browsing, I’m at 16 tabs and nearly 3GB usage on the main process. Looks like the leak still exists


  • That’s weak, I’ve gotten 3GB+ memory usage from Firefox before.

    It’s part of the reason I have 8GB of RAM installed now, RAM is cheap!

  • unknownBut2me

    Try “CleanMem” and set it to clean FF every minute or so. I do: my FF 15.0.1 has 38 tabs and is using 62,480k. I also use an add-on called “Load Tabs Progressively” and set it to load only two tabs concurrently. Works great!

  • internetexplorer

    I’m using FF 10.0.7 esr on win7x64 with 50 tabs that each have a daily usage history for the past 30 days or more, always on except I unplug my AMD 3-core with only 4 GB of RAM every few days or so for every thunderstorm (just did last night), and it is only using 400,000 K of RAM according to Task Manager. Mozilla must have made significant improvements through some of those silent updates they’re doing now, such as offloading a lot of that history from RAM to hard drive, at least that’s my guess, since I occasionally get a brief freeze when it is probably accessing that info. My experience is pretty much the same on my other computer, an AMD 2-core with 4 GB of RAM running Win7x64 and FF 10.0.7 esr, except it freezes up a little more.

  • Reymax

    2.5 gigs and only one single tab open,for atleast an hour

  • Ashraf

    @RobCr: FF 15.0.1. Not sure on how many tabs. Like I said in the post, it could be anywhere between 50-100. Using 500 MB of RAM with 450 tabs seems too good to be true — you must have been visiting very, very simple websites.
    @Vineeth Reddy: It was a long time since I had FF open. 4-6 addons.
    @Eric: Thanks for the tip on KMelon!
    @RobCr: What triggers moderation is decided by WordPress. The only rule I know of myself is the number of links, which I won’t give out because it is valuable information to spammers.
    And I have to be awake to moderate comments. :-P
    @pceasies: What?! 3.5-4GB with 30-40 tabs? The hell are you doing.
    @kelltic: Really, Opera uses up that much for you? Opera is more stable than FF in my experience.
    @anacebuyer: Good lord, 4.5GB? Here I thought I was special. Thanks for the tips and feedback!
    @lol768: Bah, I forgot to look for that. So no. :-(
    @Mike: 2GB with 20-25 tabs sounds excessive. What FF were you on? Mozilla claims to have fixed leaks in latest versions.
    @Shava Nerad: IT’S TRUE.
    @chump2010: Thanks for the tip! I may write an article on that, it sounds very useful.
    @RobCr: I was (am) on FF 15.0.1.
    @Eric: Yeah, dotTech doesn’t care about your name or e-mail. We just don’t like spammy comments.
    @fermier: Haha… it gets busy here when I’m researching.

  • fermier

    You had one hundred (?) tabs open at the same time. Perhaps reducing that to 5 or 6 might help, just a guess. No need to be greedy, the tabs should still be there if you need them later.

  • Kelltic

    @chump2010: That was very helpful chump2010. Thanks!!

  • Eric

    But overall Dottech is one of the easiest places to comment. TechSupportAlert has filters that reject comments outright without any moderation and then they edit your comments later. I understand it but it is still annoying.
    I have seen other sites where I was rejected for using a free email account like gmail and for not providing enough personal details. It looked more like a job application than a registration and I refused.
    My all time favorite registration problem was with Facebook. Their filter rejected my real name and said it was fake, so I was forced to use a fake name to register with them.

  • RobCr

    On a subject such as this (where a program can vary widely over current and previous versions) we should all make the extra effort to provide details.
    I am betting that you are not using 15.0.1, as the plugin container was a growing monster in earlier FF versions. Whereas in the last couple of FF versions it has become much much smaller, and in my situation not worth mentioning (14,600 K).

    And I suspect that Ashraf was not using the latest version ?
    (I am not referring to the plugin)

  • chump2010


    The memory problem with Opera is related to the history.

    If you go to:

    Uncheck Remember content on visited pages and reduce the history down somewhat to say 10,000 addresses. Then clear the history it will run much quicker and faster, and use much less memory.

    The problem is when it remembers all the content on all the pages (every single word is put in a database on your hard drive), then that can cause significant increases in RAM useage.

  • Shava Nerad

    You are a sick sick man. Seek help.

  • Mike

    Have gotten to just over 2GB with FF (without trying), with around 20-25 tabs open. I don’t think it was the number of tabs, though–they had been open for over a day. In my experience with FF, the memory leak over time can be severe, even with a memory management and cleaning program in operation. One of the reasons I started abandoning FF, unfortunately . . . .

  • lol768

    What about the plugin container? Is this counted?

  • anacebuyer

    I cannot comment on Firefox, but I’ve hit 4.5GB or more using Chrome. My use is similar to yours, Ashraf. I often have 70 or more Chrome tabs open on my 64GB, 750GHD, 3-coreAMD, Win7 x64 laptop. I also have a huge Thunderbird instance (often up to 1 GB to support all of the email accounts w/indexing, because I have all email since 2000 retained w/in Thunderbird). I have a screen shot if you are interested. Chrome manages each tab as a separate instance, so the memory for each session is separate. No obvious way to detect which Chrome session is hogging 240MB vs ones only needing 20MB or I’d selectively end some of the worst offenders.

    FWIW, I’ve stopped using Firefox, Waterfox, and IE 9 because they seem to use even more resources and are even less stable when I load them up this way. If my system crashes, or if I need to get to a new Wi-Fi log-in panel, I’ll often light up Opera. Maybe I’ll fiddle a bit with KMeleon.

    FWIW, I’m also running Process Lasso, and my system response is frankly pretty reasonable. It would be really, really nice if I could indicate which Chrome tabs are low priority and keep them from paging. Recently, I deleted Thunderbird from the Process Lasso management, which seems to make its performance better.

    The Office 2007 products I use seem to really be big, big challenges to my system. I’m tempted to re-install Office 2003, which seemed to run 2x faster and used much less memory.

    Hope this info is useful!

  • kelltic

    My default browser is Opera, but I also use FF. I can’t complain about FF’s RAM usage. Opera is worse for that. When either of them start running off with all the RAM I trigger CleanMem.

    The big head-scratcher is that when Opera gets hoggy, my computer heats up. That never happens when I’m using FF.

    Using XP SP3. Yes. I just love it. :)

    @RobCr: WOW 450 tabs? Really?

  • It looks a lot better than is used to be. The Waterfox variant kept crashing when I got it at 1GB (using a bunch of CSS/HTML5 benchmarks, flash and image intense websites)

    Chrome on the other hand is sitting on 2.5GB and reaches 3-4GB easy when 30-40 tabs are open.

  • RobCr

    You are correct regarding long delays when moderation is triggered.
    I have asked previously for the ‘rules’ as to what triggers moderation.
    We (dotTechies) did not get those ‘rules’

  • Eric

    If anybody is interested in trying to set the record here is a list of websites I have found to be resource hogs. I am not going to post direct links because there seems to be a magic number and I’ll get stuck in moderation for hours.
    Either indiegala or indieroyale, can’t remember which, but one of those will continually leak more and more memory if you leave it open.
    cnet’s download site
    possibly the blitzsportsnetwork
    I know there are others but that is all I can think of right now.
    As a side note, if any of you are stuck on really slow computers, by far the fastest and least laggy browser for slow systems is KMeleon. I discovered it when I recently was stuck using an ancient system with 512mb ram and usb1.1. KMeleon allowed me to open far more tabs than any other browser without totally stopping the computer. It is based on Firefox but uses windows native api. It has very limited compatibility with FF addons and I don’t think it has been updated in a little while. It is definitely worth a look if you are struggling to get more than 10 tabs open at a time. Also it does a really good job of flushing memory from closed tabs when you briefly minimize it.

  • Vineeth Reddy

    How many addons and plugins active ?

    How long has it been since you opened Firefox ?

    That is a lot of RAM usage, but chrome reaches those levels or more for the same number of tabs.

    I am sure other browsers do too.

  • RobCr

    What version of FF are you using ?
    How many Tabs do you have open ?
    How much memory was FF using, after you closed it and restarted it ?

    These are the question an Auditor and Systems Analyst would ask.

    I am using version 15.0.1 (in XP Pro SP3 PC)
    I have 450 Tabs open using 500,000 K
    I always have Task Manager running.
    I kept one eye on Task Manager, and closed FF
    Once CPU usage and Ram usage indicated that FF had truly closed, I restarted FF
    After Restart, FF Memory usage is now 380,000 K

    I have found the latest version is extremely moderate and tolerant with Ram usage
    Many times better than earlier versions.
    PS there is a setting to only load Tabs when they get the focus. Do you have that ticked ?