back to article Mozilla forces Firefox 7 on memory diet

Firefox 7 has been released with a promise from Mozilla its browser is less of a memory hog. The new version of Mozilla's browser will consume up to 50 per cent less of your system's memory than past editions with most users clawing back 20 and 30 per cent. Firefox 7 apparently achieves this thanks to a project started in …


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  1. Anonymous Coward

    The key word of course, is UPTO

    as for me Firefox 7 seems just as bloated as previous releases. It seems Mozilla are trying to get themselves out of a pickle with a crap product by applying slick marketing to the problem.

    It's otherwise more commonly known as polishing a turd.

    1. Steve Evans

      Well my experience of FF7 so far has been pretty good. I generally leave FF open with a zillion tabs in various tab groups on my laptop, and rarely shut the laptop down (takes too long to boot, so it get sleep/hibernate). FF6 would slowly leak and cause me to have to shut down the browser, restart it and then restore tabs, but so far today FF7 is being pretty good. I am seeing a memory footprint approx 40% smaller than before, and during the course of the day it hasn't proceeded to nibble its way through more and more.

      So all in all, well done Mozilla guys!

      1. dssf

        66 tabs open, 23 with pages loaded, and 135 in Too Many Tabs

        I see about 345 mb consumed RAM vice 550-640 mb. But, that might be because I restarted the browser in offline mode so the load-up excluded all the graphics. I am sure that if I refresh ALL those 42 named-but-as-yet-emptied tabs, RAM consumption will peg.

        If a page goes errant or the disk drive thrashes its ass off, i yank the ethernet to make everything time out so I can kill the errant tab.

    2. Big-nosed Pengie

      "Upto" isn't a word.

  2. MacroRodent Silver badge

    Cold day in hell...

    A new version of a large program using much less memory than the old??? Hard to believe. I have never seen it happen before. Normally bloat just grows without limits, as versions progress. Gotta test that Firefox version.

    1. Anonymous Coward
      Anonymous Coward

      And of course.

      Anyone with even an ounce of tech common sense in their head knows that to get the best performance, it's better to USE any unused memory rather than let it sit there in your system going to waste.

      The key goal is to make a memory model that can achieve the best use of what memory you have available and be able to hand it back to the host OS at any given time, a scalable rendering engine, like what Opera have, that can be run on a featurephone, a smartphone, a tablet or a desktop, with however much memory is available.

      Mozilla are playing marketing tricks on idiots, and those people that love to stuff their PC's with vast amounts of memory have just wasted their cash thanks to Mozilla's new choice to go for a small memory model over an adaptable memory model.

      1. Anonymous Coward
        Anonymous Coward

        No idea why you're being downvoted so much, because you're absolutely right. With the amount of memory in current systems, it rarely, if ever, gets used all.

        Agressive in-memory caching then seems to be a very logical choice. With this decision, Mozilla is taking a step back.

        1. Ammaross Danan


          You did read that the memory reclaimed was due to a framework or methodology of detecting and squashing memleaks, right? It's not that they unload pages that are in the background or the like, simply fixing buggy code that leaves allocated mem floating unreferenced.

      2. Orv

        Re: And of course.

        Not sure I entirely agree. I mean, I agree with your general point; but it doesn't do the user any good to have an application hanging on to memory it doesn't need. Ideally the OS should be using that idle memory for things like disk caching, but it can't if applications have it allocated.

      3. Anonymous Coward
        Anonymous Coward


        You are right but also overlooking the obvious. The task to divide memory should be left at the underlying OS, not with a single application. All memory which FF gobbles up cannot be fairly distributed between other parts of the system, and might even cause nasty side effects.

        Memory should be used, but the OS should be the ones calling the shots. Applications should only use what they need and leave it at that.

        Caching? Can be done in a multiple of ways. And here too goes my statement above; if you manage to leave it up to the OS then maybe even 3rd party programs can have some mutual benefit from it.

      4. Sam Haine

        It's not a bug, it's a feature!

        Firefox hasn't had a memory model that makes best use of memory by using as much as is available - it's just had a problem with memory leaks, among other things. That's only 'adaptable' in the sense that it will eventually waste all your memory, no matter how much you have.

      5. MacroRodent Silver badge

        Some more tech common sense

        "it's better to USE any unused memory rather than let it sit there in your system going to waste."

        Thats OK thinking in a simple single-tasking OS. Or maybe in a phone OS with one dominant foreground task.

        But in a modern multitasking desktop OS, applications cannot really know what memory is truly unused. These OS'es also do not have any protocol for telling applications "could you please give me a bit of memory back, if you dont' mind?". Applications that presume to own all memory make for a horrible user experience: Try to go to another application, or even open the desktop "start" menu or equivalent, and it's swapety swap for a while.

        Also, like the Mozilla guys note, lessening the memory footprint can improve performance even without swap problems: more of the data stays hot in the processor cache. There is nowadays a very large speed difference between accessing data already in the cache, and going all the way to main memory.

        Yes, applications should allocate more memory when they can put it to good use, and no, they may not waste it as if it were a free resource. Most of what the Mozilla developers did was hunting memory leaks and other cases where memory stays allocated for no good reason, and that is what all good software engineers should occasionally do.

    2. Chika

      Never seen a new version shrink?

      Well, I have. But then what would an old RISC OS user know?

      1. perlcat

        @ "tech common sense"

        More common sense: Applications written by pigs will run like pigs.

        I am dealing with an application written by a software design pig such as yourself, which floods my server with unreclaimed zombies as if they were the only person on the server, and not even init ought to be able to fork a process. It just wouldn't *do* to know what you need and hold your crapware to that, would it?

        If I ever find out where you live, in very short order, your doorbell will be ringing and there will be a flaming sack of dog crap on your doorstep for you to stomp out. Schmuck.

  3. Bodestone

    About time too.

    It popped up last night at home on one machine telling me that 7 was here so I thought I'd give it a look. It did seem slimmer so I used Help->About to update the other.

    All of my machines in the office are still telling me it's up to date at 6.0.2 though. Ho hum. I'll just keep closing it each night (and occasionally randomly thoughout the day on the Win7 x64 machine) for now then.

  4. Anonymous Coward

    never mind that

    Will it bugger up any important addons, like FF5&6 did??

    1. Charlie Clark Silver badge
      Thumb Up

      I don't have many add-ons: PageSpeed and Screengrab are incompatible; Firebug, NoScript, Web Developer and YSlow all are. The newer release cycle generally breaks less than the old one.

      One area I'd really like to see Mozilla work on is support for web forms. FF is as bad as IE in this respect and actually worse than IE 10 with only required and a couple of types (URL, e-mail) supported. C'mon guys, it can't be that difficult.

      Memory use in something like a browser that is supposed to use a memory cache to speed up operations is difficult to get right - the in memory cache should be as big as possible without needing virtual memory but difficult to know for an app when the OS is going to want to park it to disk - but Firefox has always had a bigger memory footprint than Opera or Chrome at start up.

    2. Anonymous Coward
      Anonymous Coward

      Add-On Compatibility

      It's 99% compatible:

      1. Cameron Colley

        Seems ScreenGrab should work.

        It works in 10.0a1, but it's reporting incompatible so you may need Add-on Compatibility Reporter installed to use it.

      2. Chika

        That may be the case, but then this whole version numbering thing that FF has going on now since the demise of FF3.x or thereabouts is a little misleading IMHO. The move from 5 to 6 was not a major move as such, and I doubt that the move from 6 to 7 will be either. Less breakage happens as a result.

  5. Ba33


    Just checked on mine, old firefox with three browser windows totalling 11 open pages used 170 ish mb, new uses 777.5mb mind you that is still a lot less than chrome with 2 tabs open is currently consuming 1.1Gb

  6. Fuzz

    I'm a big fan of Firefox but I've given up believing their claims of better performance or less memory. I like the feature set and I'm used to it so I keep it.

    Firefox 7, 1 tab open (this one) firefox is using 120MB of RAM.

    IE9, 1 tab open same page 62MB

    Chrome 80MB

    Opera 62MB

    So looks like still a way to go.

    1. Anonymous Coward
      Anonymous Coward

      RAM usage

      The change is NOT visible when looking at ONE tab.

      Do the following:

      (1) Open say 30 tabs in Firefox and then open the exact same ones in IE, Opera and Chrome.

      (2) Leave those open for say 5 mins

      (3) Check RAM usage for all

      (4) Close them and leave only one tab

      (4) Check RAM again.

      The point of the MemShrink project is that Firefox will release unused RAM much more quickly than the earlier version.

      Have a look at this:

      1. James Hughes 1

        So really, the improvement are only of use to madmen who have 30 tabs open? What about improvements for the 99% people of people who just have 5-10 open at any one time? A sane number...

        1. Anonymous Coward
          Anonymous Coward

          Number of tabs

          Firstly, I would argue that having 30 tabs open does not qualify one as a madman...

          In any event, I take your point, the above was just an example, it works just as well with the 10 tabs that (sane) people use.

        2. dssf

          I'm a MADman, man... Haven't you heard this one:

          "A clean desk is the sight of a sick mind"? I cannot limit myself to just 10 or 20 tabs. Bookmarks are not always enough, hehehhe....

  7. The BigYin

    Seems OK

    All the add-ons worked (but then I had frigged a bunch of definitions for the move to 6).

    ACID3 is no worse that it was on FF6 (100/00, but there are notices when you click on the "A").

    Memory...on tab open "El Reg" (but I have had quite a few open) and it is sucking down 353mb (and I have a lot of add-ons).

  8. Zmodem

    needs a custom temp file path, so you can store images on a temp drive and not have to wipe you main drive OS freespace every week

    1. Zmodem

      who thumbs down.. you only need 200mb partition to act as a temp drive on your home desktop PC and store all internet junk on, when loading FF it can easily create new folder that inherit user profile security settings

      you main OS drive has 90% less usage, and you only have to defrag once every 6 months.

      FF sucks not letting users set a custom path for internet junk files

      1. Richard 12 Silver badge

        You sir, fail at Google. This setting has been available from the beginning!

        Type "about:config" into the address bar.

        In the filter, type "cache" to see the settings related to caching.

        There's a setting there to completely turn off the cache if you like: "browser.cache.disk.enable"

        To choose the folder, create a setting "browser.cache.disk.parent_directory" and set it to whatever you want.

        1. Zmodem

          google sucks like the internet, and having todo all that to set a custom cache folder path is some nerdy linux rubbish

          and it wont automake needed folders on a office network, if the network has a temp file drive, to bin every month when it dies

      2. Nexox Enigma


        I can only imagine you were thumbs-downed because your idea isn't really useful. First, if you were worried about security, you shouldn't be using an OS that offers a defragable filesystem. And if you were using a decent OS, it would be trivial to store your Firefox temp files wherever you want, through mount points or symlinks.

        But mostly, thumb drives are crap. You're usually lucky to get 2MB/s sequential write on most of them, and that will add significant latency to your browsing, even on relatively slow connections. And a thumbdrive is about the last thing you should be using if you're worried about security.

        Also, though I can't be bothered to figure out, I would be willing to bet that you /can/ change the profile path in Firefox, with a bit of work, but probably without recompiling.

        1. Zmodem

          most offices use windows as the non IT work OS, most domains on a network will not have more then a 100 pc`s on, then a 1tb £45 SATA drive can be used and everyones cache folder with constant use all day and have its short life span and be chucked in the bin without no actual downtime or whatever, people just wont be able to browse all day long for a change

  9. Aquilus

    The main problem I have with Firefox is when you close it, then decide maybe 30 seconds later you need it open again (or click a link, or whatever) and it pops up a stupid 'Firefox is already running but not responding' box. Why does it take such an insane amount of time to cleanly exit? If it's compressing databases or defragging its history or reticulating splines then why on earth not do that during the hours of idle time I typically have the browser open during the day, rather than upon shutdown? And why do it every single time it closes? Modern apps shouldn't take 30+ seconds to close and go away... especially something as frequently spawned as a web browser...

    1. Anonymous Coward
      Anonymous Coward


      It takes a long time to delete the 2GB worth of pr0n in your cache!

  10. Lockwood


    Wasn't it not that long ago people were preparing to roll out FF6?

    We love these companies that keep rolling out new versions this quick.

  11. DrXym Silver badge

    A thing to remember

    Most browsers will adjust their footprint to take more memory if a PC has more memory. Open a bunch of tabs and the browser will hold the parsed DOMs of each tab plus the session history, plus compiled JS, plus parsed CSS, plus any raw files in memory if it has the space. Basically it caches stuff and will flush the cache or prune expired items when memory "pressure" gets too tight.

    Obviously that's not the same as memory leak bugs or inefficient structures which should be fixed. but personally I'd prefer my browser to utilise the space on the PC to enhance performance rather than let it stand idle when it's doing very little good.

  12. Anonymous Coward
    Anonymous Coward

    as long as it does improve

    Firefox memory diagnostics keep getting better and better, with for example js compartments shown at least to some extent, and apparently less and less dark matter (unknown) memory allocation with each release. No reason anymore to just blindly complain about 1 GB+ memory use without at least glancing at about:memory.

    Starting out with a clean profile and seeing what happens when adding the add-ons might also help pinpointing the problem (it might even be the profile is corrupted, which is why memory use is huge - it's happened to me).

  13. itzman


    I had a look at my memory, and it has containers that relate to pages I am no longer on?

  14. Anonymous Coward
    Anonymous Coward


    Are they still making that?

  15. Jim Carter

    I've been using Firefox for years

    But the screen freezes and crashes when I download even the smallest of files are starting to annoy me. Time will tell. I'll give it another couple of versions. If it stays the same, I'll have to consider shifting.


    1. nyelvmark


      I have all the major browsers installed, because I build my own website and want to check that it looks OK for everyone*.

      I used Google Chrome as my default browser for about a year, because it was so fast, but I finally got fed up with the number of websites that wouldn't render properly, and switched to Firefox. I used Firefox for about another year, but the horribly slow startup and shutdown times (I have a laptop, and I'm often changing locations) finally pissed me off enough that I decided to switch to Opera. I used Opera for only about 2 months, because the bugs and non-standard behaviour were so annoying. I've been using Safari for about a month now, and find it reasonable - it's a bit limited (especially compared to Firefox) but seems to be stable, and to work with every website I've visited so far. Of course, if your system is different from my Vista installation with 2G RAM, your mileage may vary.

      I think I may have forgotten to mention IE, but I'm fairly confident that you're not considering that as an option. If you are, you're on your own.

      I hope this helps.

      *Yes, I realise that pro web designers don't do this. I'm such an amateur that I even bother making sure that my HTML and CSS validate.

    2. Anonymous Coward
      Anonymous Coward


      I've just moved from Chrome back to FF for the same reason.

  16. Jon Smit

    It deleted No Script

    Firefox v7 removed No Script when it installed. There are no compatibility issues, it decided to removed this important Add On and keep bloody quiet about it.

    I contacted the developer of No Script, Giorgio Maone, and discovered I'm not the only user to have the same problem.

    Obviously, No Script is doing too good a job.

    1. EddieD

      Not here

      Seeing this article prompted me to upgrade - Noscript and Adblock both survived the upgrade.


    2. Kevin 6

      Did the same to me.

      Also deleted another addon I used to block stuff. Wish I could remember its name so I could re-install it

    3. Number6

      Me Too!

      Yes, I fired up FF7 and noticed that a page that should have failed didn't, and discovered the lack of NoScript. Immediate re-install at that point.

      1. Number6

        But not always...

        I upgraded the laptop and it didn't lose NoScript. However, I'm not sure whether that's because it already had the latest version of NoScript installed (FF rarely gets restarted on my desktop machine so updates are relatively slow) or some other mysterious cause.

    4. Anonymous Coward
      Anonymous Coward

      this is odd

      As it also deleted my buddies no script but not mine. Odd

  17. E 2

    It *should* use less RAM

    Having removed the status bar, the menus and almost all the other user feedback widgets, Firefox should use less RAM... there is less browser there.

  18. Sim

    no script

    The upgrade also silently deleted no-script for me. However I was warned that page speed and HTTPS everywhere were not compatible.

    Also my Live Bookmarks now all report "Live Bookmark Feed failed to Load" but they do update when I ask them to reload manually.

  19. Sporkinum

    Had to revert back to 6.02

    I saw the update last night, and downloaded and installed it. I lost NoScript and Adblock+. That is a no go for me, so I re-installed 6.02 and then everything was back to normal.

    I also saw here at work that 6.02 is considered up to date, and that there is no update pending.

  20. The Fuzzy Wotnot

    Needs a serious kick up the wotnot!

    I recently gave Chrome a go and was so surprised how lightning fast Chrome is opposed to Firefox. I was trying to get some tickets just after they went on sale, so refresh was utmost importance. FF was coming in at 7-10 seconds on the page, Chrome was hammering home at 2-3 secs.

    1. Anonymous Coward
      Anonymous Coward

      FF have lost the plot...

      I'm with you there. I gave chrome a go when the update frequency nonsense first started. When ff FUBAR'd most of my addons and realising it would keep doing this in half-yearly increments, it was time to switch. Chrome, while not perfect is much more predictable than FF and just as fast.

      I'm all for FLOSS but please don't make me jump through hoops (compatibility tweaks), just to get back to where I was.

  21. Mystic Megabyte

    All the usual add-ons working in FF 7.0 except Convergence which was disabled by the updater.

    Flash works.

    Running Ubuntu 10.10 64bit.

  22. jhermans

    This is just a preview — your post hasn’t been submitted yet.

    Sigh. Every time an update is released, you can always read the same clueless comments. If you really think you know better, you can easily fix it yourself. The source code is open. I don't work for Mozilla, but there's some of my code inside (even though I'm mostly a bug triager). Obviously, only the improvements that are ready (and went thru a 12-week test cycle) are included, and there is more to come. There will always be.

    @Martijn Otto: are you kidding ? Everyone asks to use less memory, and you want to use more? Note the memory savings have not been done by removing caches.

    @Aquilus: never saw that, it only last a few seconds at the most. Check your add-ons.

    @itzman: the new version is already improved a lot (note that you couldn't see the compartments before), but there indeed cases where compartments are immediately released. At least one of the vectors is AdBlock+, but there others too. In many cases, the compartment will be released a while later (reloading the website again), but it often depends on the exact JavaScript code that is used by the website).

    @EddieD: AdBlock+ works fine

    @The Fuzzy Wotnot: let me guess, you tested on Google website ? Look up what SPDY. means..

  23. Anonymous Coward

    Gah... arghhh ! anger!

    You know, call me crazy ("your crazy"), but recently, I went back to 3.6 for dev work.

    The back story here is that I've been a firefox user since it was firebird, some centuries ago now in net time. When 4 was released and showed itself as a rather unwieldy beast - more fatfox than firefox - I switched to the new kid on the block, chrome, as my primary 'surfing' browser.

    However, I was so tied to my firefox extensions, most specifically developer extensions, I kept firefox as my dev browser.

    I'd frequently find my work dev machine slowing to a crawl, only to find good old fatfox was having a little munch on my memory whilst I wasn't looking.

    I disabled all but my most essential extensions. It failed to assist, fatfox just kept on munching away, turning my PC into a big fat slobby sweating panting mess. The fattest fat kid at school trying to run crosscountry whilst eating mars bars, so fat, he blocked the path of the skinny fast kids.

    I finally decided to snag fatfox 7 today and have found that the fattest fat kid has got himself a bicycle. He's still a big old bloater, but he can move a little faster.

    Oh, mozilla, where did it all go wrong?

    Please, go on a diet, shed some pounds, bring us back that super fit marathon runner of old, that Phoenix that rose from the ashes of netscape.

    In the interim, I'll keep getting angry at you, I need you firefox, I can't kick the habit... just like the fattest fat kid with his stash of mars bars...

    1. Turtle_Fan
      Thumb Up

      Marvelously put.

  24. Anonymous Coward
    Anonymous Coward

    I suppose...

    That all the requests for a smaller, faster browser just got delayed in the e-post for the past several years.

  25. Neoc

    Big problem with checking memory usage.

    Most people look at what Windows (and I assume Linux) reports as the memory usage for FF and complain that it hasn't shrunk. Please do not forget that this number includes both the browser AND THE PAGE DATA.

    A properly written browser (and FF may or may not be one, I am not a browser expert) would have a small *browser* memory footprint (which can't really change all that much over time/use) and a large-but-flexible *data* memory footprint (able to be shrunk at a moment's notice if required).

    Unfortunately, most memory-reporting tools do not (cannot?) differentiate between the two and simply report on the total usage.

  26. Anonymous Coward
    Anonymous Coward

    They'll stop the memory leaks

    around the same time Duke Nukem Forev... oh fuck.

  27. jhermans

    Issue discovered with Firefox add-on upgrades

    People who lost one of their add-ons after upgrading, please read for some info and a workaround.

  28. Richard Pennington 1

    Just updated one machine to FF7 - the installer silently dropped Adblock+, NoScript and Flagfox. Two other machines are reporting that FF 6.02 and 5.0 (!) are up to date.

  29. Richard Pennington 1

    Dropped add-ons: it's a known Firefox bug

    Check out

    Apparently when there is a pending update to the add-on which has not been installed when the version of Firefox changes, Firefox drops the add-on entirely.

    So it affects primarily add-ons which are frequently updated.

    [Source: via Noscript user forum]

    1. asdf

      QA is for losers

      Wow so once again firefox testing before release is half ass. And they wonder why everyone hopped on the chrome train.

  30. Relgoshan


    What the hell are these guys doing? Shipping a major version with crippling extension bugs....

    At least they've finally gotten serious about the pile of piss hanging up your whole OS for five-ten seconds running garbage collection, and this new deallocator gives back more resources too. Still a hog but not quite as hungry.

    Any other grade-school basics in the works? Like summoning the menu with the keyboard while in fullscreen? Fixing the awful Downloads manager?

  31. JMcL

    Still memory hungry as ever

    FF 7 is still routinely chewing up well over half a gig of memory on my work PC, with not a huge amount of stuff open (in number mainly tabs of El Reg stories).

    The only real reason I'm sticking with it is Adblock which every time I see a non-adblocked site I realise I can't live without. At this stage though I'm tempted to try Chrome with their version

  32. Anonymous Coward

    Upgrades and Addons...

    What they do...

    Install the updates and then tell you that they are checking your add-ons for compatibility, but woops, sorry!

    A Better idea...

    Check your environment first. This doesn't seem to have occurred to them.

    Ubuntu upgrade keeps offering me a FF uppdate. I'm not accepting it for a while yet. I've already been through the downgrade-and-lock-version with Thunderbird --- because the upgrade was not compatible with Lightening, and I am that singe person in the world that uses it! They can't even update their *own* add-in projects for a version change.

  33. Anonymous Coward
    Anonymous Coward

    To the numpties ...

    ... who think that they saved memory by less caching please read this:

    It was about tackling efficiency problems. (About time).

  34. stupormundi

    frikkin FF 7

    I was happy when I first read FF7 would use less mem. I've got a slow netbook with a gig of RAM, FF was typically eating most of my ram.

    Now that I have FF7, as soon as I have a couple tabs open (like 4 or so), the bloody thing starts to use up most of my CPU cycles for long periods of time. Irritating as hell. First I suspected bad JS on specific pages to be the cause, but after seeing it consistently no matter where I browse, I'm thinking it must be the brower itself.

    And I'm not sure it really does use much less ram. It does at the moment, because I don't dare open more tabs. Aaaargh.

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