Firefox Too Slow? Optimise Your Browser With These Tricks

Danny Stieben 22-01-2014

Firefox keeps getting faster – so much that it’s starting to tie Chrome – but for some people it’s just never fast enough. If you want to get the absolute best performance, you’ll need to tweak some under-the-hood settings so that they prefer performance over convenience. Here are a few tips which you can use to get that extra speed boost.


Disclaimer: While none of these tweaks should break Firefox, your actual results may differ and are not guaranteed.

Firefox Booster

If you’re on Windows, the first thing you can do is download Firefox Booster and run it. This little application will go into the under-the-hood settings for you and make some changes in all versions of Firefox (despite it only mentioning v1, v2, and v3). This app works entirely on its own, except for when it asks what type of connection you have – slow, medium, or fast. This is important, because it tells the app what values it needs to put into the settings.

This app goes into Firefox and changes the maximum amount of connections – how many web servers Firefox can connect to at a single moment – and pipelines – the number of streams that can be used to download content – that Firefox creates when connecting to a website.

If you have a fast connection, you’ll want to have Firefox use more connections and pipelines, so you can download more content concurrently. If you have a slow connection, you’ll want Firefox to use fewer of these, because otherwise all the pipelines will start to bottleneck each other and actually slow down performance. Firefox’s default settings are meant to be good for all connections, but they won’t be ideal unless you have a “medium” connection.

Firefox Booster comes with a few additional settings which aim to help increase Firefox’s performance, such as disabling blinking text, optimizing Firefox’s memory usage, and showing error messages as a web page.


Additional Tweaks

If you’re not on Windows, you can do the same network tweaks using the Tweak Network extension, which should work on all platforms. You can type in your own values if you’d like, or just go for the “power” preset for fast Internet connections.

To use the rest of the tweaks, we’ll need to type about:config into the address bar and accept the warning that appears on the following page. After this, you’ll see a very long list of variables which determine Firefox’s behavior – we’ll only want to change a few of these.

Again, this shouldn’t break anything, but your results may vary.

  1. Type browser.sessionhistory.max_entries into the filter box, double click on the result, and change it to 10. This reduces the maximum amount of URLs that Firefox will keep in its history, which in turn minimizes disk usage as well as the amount of times Firefox needs to access something from the disk – usually the slowest part of your computer.
  2. Right-click in the empty white space below the only entry, and choose a new Integer entry. Type in nglayout.initialpaint.delay for the name and 0 for the value. This will speed up page loading by intentionally telling Firefox to avoid waiting during certain parts of page loading.
  3. Type browser.cache.memory.enable into the filter box, and double click on it to set it to True. This will allow Firefox to place some of its cache in memory so that it can load pages faster. The cache is a collection of websites and web content that you’ve downloaded by visiting it before. Usually cache is stored on the disk, but this enables at least some of the cache to be loaded into memory for faster page loading.
  4. Right-click in the empty white space below the only entry, and choose a new Integer entry. Type in browser.cache.memory.capacity for the name. For the value: set it to 2048 if you have 128MB of RAM, 4096 if you have 256MB of RAM, 8192 if you have 512MB of RAM, or 12288 if you have 1GB or more of RAM. This sets the amount of memory that can be used to hold some of the cache.
  5. Type browser.cache.disk.capacity into the filter box, double click on the result, and change it to 4096. This means less disk space will be used for the cache, which will reduce disk usage and increase performance if you use a traditional hard drive. Solid state users can probably skip this as those drives are nearly as fast as memory.
  6. Right-click in the empty white space below the only entry, and choose a new Boolean entry. Type in config.trim_on_minimize for the name, and set it to True. This will make Firefox clean up some of its memory usage by trimming unneeded items whenever Firefox isn’t being actively used (aka, minimized).
  7. Optional: If you want Firefox to only load pages and content that you want (when you actually click on a link), you’ll want to disable prefetching. Type network.prefetch-next into the filter box, and double click it to set it to False. It’s arguable whether this results in any performance increases, but it definitely saves you a bit of data usage. This is certainly important to do if you find yourself regularly tethering to your smartphone.

How To Revert Back

If you went through the manual about:config tweaks, reverting them back to normal is easy. If I had told you to create an item earlier, then just delete it. If I told you to change the value of an existing item, simply find it, right-click on it, and choose “Reset”. This will bring it back to its default setting.



Hopefully these tricks will give you some boost in performance. If you didn’t see a noticeable difference, then either your system is super fast already, or your Internet connection is the real bottleneck (assuming you get similar performance out of other browsers as well). Don’t forget to check out some other articles aimed at improving Firefox’s speed, such as using QuickJava in Firefox Speed Up Firefox: Use QuickJava To Block Flash, Silverlight And More Is your browsing too slow? Block the stuff that's bogging you down. QuickJava is a simple Firefox extension that gives you the ability to temporarily turn off browser plugins and make Firefox faster. Read More or following these 5 great tips if other browsers work fine 5 Things to Do When Firefox Runs Slow (But Other Browsers Run Fast) If Firefox feels slow compared to other web browsers, try these tips to see if you can boost its speed and restore its performance. Read More .

Don’t forget to check out our User’s Guide to Firefox The User's Guide to Firefox Does your current browser have advanced security options? Does it sync your settings across devices? Can you manage your tabs easily? These are all things Firefox can do for you. Read More to get the most out of the popular open source browser!

What’s your favorite tweaks to Firefox? Let us know in the comments!

Related topics: Bandwidth, Mozilla Firefox.

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  1. Asok Asus
    July 9, 2014 at 12:58 am

    I’ve just been FED UP with FF because of all of the memory leaks, etc. I've been running v16 forever because whenever I’ve tried to upgrade to newer versions, they’d all pretty much just crash after 30 minutes of heavy use, and not a single version of FF that I’ve ever used has ever fixed the memory leak problems. Not a single one.

    I actually installed a tiny batch file on quicklaunch so I could quickly kill FF at the point it’s consumed all of my RAM so I could then start over with “Restore Session” to automatically reload all of my previous tabs. After trying every “solution” to the leak problem, that’s the only one that ever did me any good. Apparently the arrogant tards at mozilla would rather tweak the UI to death rather than make a browser that actually works. They’re worse than even Microsoft because Microsoft has to listen to their customers sooner or later or go broke, whereas nonprofits can just drift along forever.

    At any rate, I just finished installing PM, including importing everything from FF with their little importer program, and everything went flawlessly, including all settings and the plethora of add-ons I use. The only difficulty was getting roboform attached, which I can’t live without. I did finally dumb around and got the roboform taskbar program to attach roboform to PM, which then worked flawlessly. It is, however, necessary for the roboform taskbar program to run all the time for roboform to continue to work on PM, but this is a very small price to pay to ditch FF forever.

    I've used PM for a week now, opening/closing/keeping hundreds of tabs a day, and I’ve been stunned at how much faster PM is than FF, as well as the VERY small memory footprint occupied by PM vs FF. Even after a week's HEAVY usage, PM has not grown beyond 1 GB, and even better, when I close tabs, ALL of the RAM is given back.

    Basically, PM is what FF ought to be. Even better, the genius behind Pale Moon, Mark Straver, has committed to keeping the PM UI fundamentally unmolested. I’ll be installing PM instead of FF on all of my client’s computers in the future as well!

    (BTW, ALL of the "recommended fixes" for the firefox memory leak problems are a sick joke. Not one of them works. And plugins DO NOT cause the memory leaks! Firefox does! How do I know? Because I switched to Pale Moon, importing everything EXACTLY like it was in Firefox and guess what? No memory leaks in Pale Moon! Oh, and I use Adblock Plus, Flash, Java, DoNotTrackMe, BetterPrivacy CookieCuller, DownloadHelper, Element Hiding Helper, IE View, ViewAbout, Visited, and roboform. So NONE of those is causing the firefox memory leak problems!)

  2. Frozenx
    February 15, 2014 at 10:03 am

    Do I have to continuously run firefox booster when using FF, or just need to run for 1 time from beginning then all stuffs get done.

  3. Karl J. Gephart
    January 23, 2014 at 12:00 am

    Same old outdated Firefox registry "tricks" that do very little if anything in my experience. Today's article on ghacks proves my point:

  4. stuart
    January 22, 2014 at 8:16 pm

    My Firefox is super fast on ubuntu, except for the terrible rendering speeds of Google maps and any other canvas rendering in JavaScript. I didn't see anything in here for that.

    • Danny S
      January 31, 2014 at 8:21 pm

      That may have something to do with the open source drivers (or maybe even proprietary drivers) in combination with Firefox's hardware acceleration. Just an idea for troubleshooting.

  5. Tim
    January 22, 2014 at 6:47 pm

    The solution to Firefox being slow is to use Google Chrome instead. If you have to tweak your browser to make it run "better" then why not just use one that already does?

    • Skrell
      January 23, 2014 at 1:23 am

      Umm...i dont know about bc many Chrome addons/extensions are spyware? Or maybe because Google is known to willingly hand your information over to the NSA?

    • Tony Karakashian
      January 23, 2014 at 5:41 pm

      I hear this all the time, but I switched back to Firefox from Chrome because of the significant performance hit I took using it.

    • Enrique Iglesias
      November 19, 2015 at 4:24 pm

      chrome is slow and sucks . firefox is really faster then chrome and safe them too

  6. Jorden
    January 22, 2014 at 6:46 pm

    The only thing slow about Firefox is the start up speed. With memory and processors being so cheap, no reason for Firefox to be slow while browsing.

  7. Jay I
    January 22, 2014 at 5:30 pm

    That said, this is a good and useful article - and if memory, processing power are no limits - then FF Booster sounds like a really cool tool to speed up FF. Thanks for writing this.

  8. Jay I
    January 22, 2014 at 5:27 pm

    Firefox has always been super slow for me. Chrome is a browser I like - even with Ad-block I get super good performance when using Chrome compared to Firefox. And I don't think its only the internet speed that matters - the processing power, the available memory on the computer - all contribute to Firefox's speed. I've never used FF without it utilizing more than 0.5 ~ 1 GB of RAM. Its insane how much RAM FF needs to run - even without any extensions or themes - at its bare skinned version.

    • Jay I
      January 22, 2014 at 5:28 pm

      That said, this is an interesting article on FF booster - thanks for the tips!

    • XtremWise
      January 24, 2014 at 1:56 pm

      Chrome browser is spyware...

    • Danny S
      January 31, 2014 at 8:20 pm

      A lot of people have noticed that Chrome has become a lot more bloated as far as memory usage goes since its initial release. Food for thought...

    • dragonmouth
      February 3, 2014 at 5:59 pm

      It is not only Chrome that is getting bloated. Most software, as it is "improved" gets bigger. It's called "feature creep."

      When Firefox made its debut as "Phoenix" it was slim, trim, fast and took up relative little RAM. It also has very few add-ons. Over the years and iterations, FF acquired new names, more features and more add-ons. It became bigger and slower, and a bigger hit on RAM.

    • anon1
      March 11, 2015 at 2:23 am

      Definitely untrue.... Just opening 2 tabs with adblock as extension eats like 1gb-2gb of ram.... And the lag/stutter/delay becomes noticeable when you open 5 or more tabs even on my high end i7/8gb ram computer. And obviously Firefox had been under the finger of Google when they formed a contract a couple of years ago hence it looking like google chrome due to it and google butchered it little by little till their contracts expired. Just hope that FF return to its origin after they separated from the hands of google.

  9. dragonmouth
    January 22, 2014 at 2:19 pm

    "Firefox too slow?"
    Disable most of your plugins and extensions. Yes, they provide a lot of convenience but convenience comes at a price. Each plugin and extension is another program that has to run and use CPU cycles. Not only will Firefox be slowed down but so will the entire system. Load enough of them and they may even stop FF altogether. These and other tweaks will speed up FF but only if not too many plugins are loaded.

    If I am not mistaken, not too long ago MUO ran a poll on how many browser plugins and extensions people have added. It seems most users had over 50 plugins installed, with quite a few users having over 300 installed. With that many extensions no amount of tweaking will help. Even going to a faster system (m/b, RAM, SSD) will not help. With that many plugins, Firefox and any other browser will always be a pig.

    • Danny S
      January 31, 2014 at 8:18 pm

      This is very true. People should definitely look at what plugins and extensions they have installed. These are just some under-the-hood changes for those that are already running slim in terms of extensions.

    • Aeronomer
      September 14, 2016 at 9:17 pm

      The only extension I have on FF is one that alters the look of the browsers buttons and so forth. Yet, even on my high-end desktop at home, I still find websites with lots of flash ads will bog it down relentlessly. The ONLY solution I've found to help is using the NoScript addon. A web page that has so much crap on it that I can't even scroll down the page effectively works like a charm when I have NoScript running. It can be a little annoying to figure out what scripts to allow (say, to watch a video) on some pages, but it's worth the one-time hassle.