5 useful Firefox tweaks

Firefox is a great browser, and part of that is it's extensibility. As well as extensions and themes, Firefox also has an extensive set of hidden preferences that you can't get to through the graphical Preferences dialogue.

Instead, you can access them via the built-in about:config URL (just visit that in Firefox).

#1 - setting cookies for 'sites you navigate to' only

In a strange move backwards, this feature disappeared from the graphical Preferences dialogue as of Firefox 2.0. What it does is that it only sets cookies for sites you actually visit (i.e., not intrusive advertising programmes).

From about:config, search for cookie and find network.cookie.cookieBehavior Double-click it and change the value to 1.

#2 - set backspace to go back a page (Linux only)

As of Firefox 2.0, pressing backspace no longer heads back a page under Linux. Fix this by searching for browser.backspace_action and change it to 0.

#3 - always display menu bar in popups

Legitimate popups are great, but sometimes it's nice to have access to the Firefox menu bar in the popup.

Again, in about:config, find dom.disable_window_open_feature.menubar and double-click it to toggle it on.

#4 - always display toolbar in popups

Just like the last one, but this will show the toolbar instead of the menu bar in all popups.

You'll need to double-click on dom.disable_window_open_feature.toolbar to toggle it on.

#5 - disable installation of extensions and themes

If you're setting up Firefox in a configuration where you don't want people messing around installing extensions and themes, you can easily disable them.

Note - it's easy to get round, as anyone else who knows this tip can browse to about:config and can reverse the setting, so it will only deter casual meddlers.

Search for xpinstall.enabled and double-click it to toggle it off.

Parting words

This was just a very quick round-up of little Firefox tricks you might not have known about. I'm sure there are many more good ones, so if you know a killer about:config hack, let us know in the comments!

UPDATE: aussiebear posted a great #6 in the comments, so I've reposted it below!

Here’s number 6: Reduce memory consumption.
(Tested on both Windows AND Linux versions).

In Firefox, enter in the web address line:
=> about:config

Then enter in the “Filter” line:
=> browser.cache.disk.capacity

Based on how much system memory you have enter the following to modify the value:

For 128MB to 512MB RAM => 5000
For 512MB to 1GB+ RAM => 15000
(These are typical values that work for most people. You may use other values if you wish, depending on your web surfing habits).

Then restart Firefox.

For some stupid reason, they set it to something like 200000 by default!

You wonder why Firefox consumes 100+ MB of RAM!

I can also confirm that this works with the Mac OS X version of Firefox too, so if Firefox is being a memory hog, give this a try. Thanks aussiebear!

Avatar for peter Peter Upfold - http://peter.upfold.org.uk/

Peter Upfold is a technology enthusiast from the UK. Peter’s interest in Linux stems back to 2003, when curiosity got the better of him and he began using SUSE 9.0. Now he runs Linux Mint 9 on the desktop, runs a CentOS-based web server from home for his personal website and dabbles in all sorts of technology things across the Windows, Mac and open source worlds.

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Discussion: 5 useful Firefox tweaks

  1. Cliff (guest)

    # Posted on 28 February 2007 at 05:47 PM

    Very nice, keep them coming! I only used the cookie hack, would love to see more. Always glad to see this sort of stuff published. Thanks!



  2. aussiebear (guest)

    # Posted on 01 March 2007 at 02:50 AM

    Here's number 6: Reduce memory consumption. (Tested on both Windows AND Linux versions).

    In Firefox, enter in the web address line: => about:config

    Then enter in the “Filter” line: => browser.cache.disk.capacity

    Based on how much system memory you have enter the following to modify the value:

    For 128MB to 512MB RAM => 5000 For 512MB to 1GB+ RAM => 15000 (These are typical values that work for most people. You may use other values if you wish, depending on your web surfing habits).

    Then restart Firefox.

    For some stupid reason, they set it to something like 200000 by default!

    You wonder why Firefox consumes 100+ MB of RAM!



  3. Peter (guest)

    # Posted on 01 March 2007 at 09:19 AM

    I've reposted in the main article. Great tip, aussiebear!



  4. Chris (guest)

    # Posted on 01 March 2007 at 05:33 PM

    browser.cache.disk.capacity has nothing to do with RAM (well, it's probably somehow linked, but the values have nothing to do with RAM). Here's Mozilla's definition of that entry:

    "When a page is loaded, it is cached so it doesn't need to be downloaded to be redisplayed. This preference controls the maximum amount of hard drive space to use for caching purposes. [Enter the] maximum amount of hard drive space in KB to use for cache [as an integer, default is 50000]."

    You can also access that in a GUI, Tools -> Options -> Advanced -> Network / Cache



  5. Chris (guest)

    # Posted on 01 March 2007 at 05:34 PM

    Are you thinking of "browser.cache.memory.capacity"? Mozilla sayz:

    "When a page is loaded, it can be cached so it doesn't need to be rerendered to be redisplayed. This preference controls the maximum amount of memory to use for caching decoded images and chrome (application user interface elements)."



  6. aussiebear (guest)

    # Posted on 02 March 2007 at 05:53 AM

    I guess I have to defend my tip.

    On Windows 2000 (when I used to use it), Firefox used to skyrocket to over 170MB+ RAM. That's with the default settings.

    Once I implemented Tip #6, the RAM consumption never went beyond 96MB.

    This is based on my surfing habits of opening 30 tabbed windows and viewing YouTube videos.

    On Linux, things are even better. It stays around 85MB of RAM. It used to use over 120MB+.

    All I'm saying, just try it for yourself.

    Grab a collection of sites.

    Boot up your system, run Firefox, visit those sites. Once done, note the RAM used. Clear Cache.

    Implement Tip 6.

    Reboot system, revisit those sites. Note the RAM consumption.

    You'll see a drop.

    Why does it happen? I don't know. I am not a programmer. I wish I was. If I had the skills, I would re-do Firefox in assembly language. :D



  7. Chris (guest)

    # Posted on 02 March 2007 at 09:16 AM

    Yeah, I'm sure it's somehow connected, it probably has to do with the caching process being RAM intensive.



  8. ttancm (guest)

    # Posted on 19 March 2007 at 07:11 AM

    Even if #6 is connected to RAM use there's no reason to set it via about config? It's mentioned above, but you can set it directly from Tools->options->network->cache

    And it has no effect on memory usage for me on FF2.0.0.2 WinXP SP2 2gigs ram.

    I open up a ton of stuff (especially flash) and firefox shoots up to 200mb RAM used no matter how low I set that. It actually makes things worse if it's set too low because then I have to re-cache things when switching tabs if it dumped something because of the low setting =P



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