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There is now a Firefox extension that will change most of the about:config entries for you. The easiest way to tweak Firefox is simply to install the FasterFox extension, which can be found here.

Note: There is quite a bit of debate about the merits of FasterFox's "prefetch" function. If a lot of people begin using it, it could drive smaller websites under with enormous bandwidth costs. Many small website owners are beginning to ban Firefox+FasterFox users as a result. Please read the FasterFox user comments before enabling the "prefetch" feature in this plugin.

Little Firefox Knowledge Snippets


From Mozillazine
Beginner's Information
All settings can be adjusted by browsing to "about:config"

Table of Tweaks
NOTE Values for connections (http, proxy, etc) should be tweaked and timed based on connection, these are setup for my 1.5Mb cable connection

Key Value Description
network.http.pipelining true enable pipelining for normal connections
network.http.proxy.pipelining true enable pipelining for proxy connections
network.http.pipelining.firstrequests true enable pipelining of first requests
network.http.pipelining.maxrequests 8 maximum HTTP requests per pipeline
content.notify.backoffcount 5 number of initial reflows during rendering
ui.submenuDelay 0 context menu popup delay
content.interrupt.parsing true enable interruption of parsing to return to the application's event loop
content.max.tokenizing.time 2250000 time after which parsing is interrupted
content.notify.interval 750000 time steps for the initial reflows (content.notify.backoffcount)
content.notify.ontimer true enable timer based reflows
content.switch.threshold 750000 keep same as content.notify.interval
nglayout.initialpaint.delay 0 time before inital page reflow
network.http.max-connections 48 number of total HTTP connections
network.http.max-connections-per-server 24 maximum number of any type of connections per server
network.http.max-persistent-connections-per-proxy 16 maximum number of keep-alive type connections per proxy
network.http.max-persistent-connections-per-server 8 maximum number of keep-alive type connections per server
browser.cache.memory.capacity 65536 size of memory to use as cache - set as big as you can for normal operation
network.dns.disableIPv6 true disables IPv6 support - may not work for all networks, some report speed increase

User Script Hacks

Firefox lets you edit the default UI by editing the user scripts in .mozilla/firefox/[userhash].[profilename]/chrome/

You can place your tabs horizontally stacked along the sides of your browser window with this added to your .mozilla/firefox/[userhash].[profilename]/chrome/userChrome.css :

    /* Display the tabbar on the left */
    #content > tabbox {
        -moz-box-orient: horizontal;

    .tabbrowser-strip {
        -moz-box-orient: vertical;
        /* note: you can set this to -moz-scrollbars-vertical instead,
           but then the scrollbar will *always* be visible.  this way
           there is never a scrollbar, so it behaves like the tab bar
           normally does */
         overflow: -moz-scrollbars-none;

    .tabbrowser-tabs {
        -moz-box-orient: horizontal;
        min-width: 20ex;   /* you may want to increase this value */
        -mox-box-pack: start;
        -moz-box-align: start;

    .tabbrowser-tabs > hbox {
        -moz-box-orient: vertical;
        -moz-box-align: stretch;
        -moz-box-pack: start;
    .tabbrowser-tabs > hbox > tab {
        -moz-box-align: start;
        -moz-box-orient: horizontal;

   /* remove the close-tab button */   
    .tabbrowser-tabs > stack {
        display: none;

You can change the UI font with this also in userChrome.css:

* {

    font-family: "FONT_NAME";


Adding searchplugins

Firefox makes it very easy to extend the search bar (right next to the URL), which it provides for easy access to all kinds of web searches. All search engines that appear in this list have a corresponding entry in /opt/mozilla/lib/firefox-xx/searchplugins (one .src and one .png file for each search engine).

To add engines to this list, you can go to or even install an Arch-specific list with pacman -S arch-firefox-search.

  • Hint: How to change the order of your searchplugins list
    • You can now (in Firefox 3) change the order in the GUI. Open the dropdown list of search engines and click Manage Search Engines... . Highlight the Engine you want to move and use Move Up or Move Down to move it.
    • (Earlier Versions) I created the folders A, B, C, D, E, ... within .../searchplugins and dropped the .src and .png files of each searchplugin into one of these folders. Now they are in order.

See also Wiki page about adding Search Engines

Q: If Mozilla Thunderbird is open, Mozilla Firefox refuses to open.

A: This is a problem with the way that Firefox is packaged. Open /usr/bin/mozilla-firefox in your favourite text editor and comment out all lines of code. Add the following line instead:

exec /opt/mozilla-firefox/bin/firefox ${1+"$@"}

How to prevent plugins from allowing popups?

Ever wondered why popups appear even though you've blocked them? It seems that Flash plugin can bypass default settings and annoy us with those pesky popups. Fear not, for we can prevent it from doing that.

To get around it:

  1. Type about:config into the Firefox location bar.
  2. Right-click on the page and select New and then Integer.
  3. Name it privacy.popups.disable_from_plugins
  4. Set the value to 2.

The possible values are:

  • 0: Allow all popups from plugins.
  • 1: Allow popups, but limit them to dom.popup_maximum.
  • 2: Block popups from plugins.
  • 3: Block popups from plugins, even on whitelisted sites.

Turning off anti-phishing to speedup Firefox

The anti-phishing features of Firefox may cause Firefox to become slow to start or exit, and might also affect the browsing speed since Firefox apparently contacts google for every http request. The problem is that Firefox maintains a sqlite database that might grow quite big, and reading and writing to this database begins to take some time when it grows bigger. If you feel that you don't need Firefox to tell you which sites may be suspect you can disable this feature:

  1. Turn off the following options under the security tab in preferences: "Tell me if the site I'm visiting is a suspected Attack site" and "Tell me if the site I'm visiting is a suspected forgery".
  2. Delete all files beginning with urlclassifier in your profile folder (~/.mozilla/firefox/********.default where ******** is some combination of letters and numbers. default might be something else if you have created a non-default profile). Some of these files might be recreated by Firefox, but they won't grow any larger than their initial size.
rm -i ~/.mozilla/firefox/*.default/urlclassifier*

Note: Deleting files from your profile folder is potentially dangerous, so it's recommended that you make a backup of the folder first.

Common Problems

These problems are not bugs, just issues that may not be apparent.

Small fonts after upgrade

After upgrading to xorg7 some users have had fonts become too small in Firefox. Edit > Preferences > Content > Fonts & Colors > Advanced > Display resolution > System setting fixes the problem. Just changing the default fonts around doesn't.

Firefox hangs when trying to download files or images

If you use the deafault supplied simple_firewall.rules with iptables for your firewall and you have gnome-vfs installed you might be in trouble. Quoting Jan De Groot: "gnome-vfs calls FAM. To find out if FAM is reachable, it tries to contact portmap... which will take ages when your localhost interface is firewalled." So add something like

-A INPUT -i lo -j ACCEPT

to your rules. This is due to the "famous GNOME/KDE loopback issue" which slows down all your GNOME and KDE activity.

How to open a *.doc automatically with abiword or open office

1) Thunar (the explorer of xfce) Link doc with the abiword icon Search a *.doc -> right click this *.doc file -> open with -> other application -> select abiword (or Open Office Writer) 2) Firefox Edit -> preferences -> file types -> manage -> doc file -> Open them with this application -> /usr/bin/abiword (or /usr/bin/soffice)

There is also a plugin/addon called mime edit. This addon will let you edit the mime types for firefox.

External Links