Firefox/Tweaks

Related articles

• Firefox
• Browser Plugins
• Firefox Ramdisk

This page contains advanced Firefox configuration options and performance tweaks.

Performance

Improving Firefox's performance is divided into parameters that can be inputted while running Firefox or otherwise modifying its configuration as intended by the developers, and advanced procedures that involve foreign programs or scripts.

Note: Always use the latest version of Firefox.

Advanced Firefox options

This section contains advanced Firefox options for performance tweaking. For additional information see these Mozillazine forum posts.

Network settings

Advanced network settings can be found on the about:config page (try searching for network).

Recommended values for a 1.5Mb 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.maxrequests	8	Maximum HTTP requests per pipeline
network.http.max-connections	64	Maximum number of total HTTP connections
network.http.max-connections-per-server	16	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
network.dns.disableIPv6	true	Disable IPv6 support

Note: These settings need to be configured based on your connection.

Turn off anti-phishing

Note: Deleting files from your profile folder is potentially dangerous, so it is recommended that you back it up first.

The anti-phishing features of Firefox may cause Firefox to become slow to start or exit. The problem is that Firefox maintains an Sqlite database that can grow quite big which makes reading and writing slower after repeated use. If you feel that you do not need Firefox to tell you which sites may be suspect you can disable this feature:

• Turn off the following options under the security tab in preferences: "Block reported attack sites" and "Block reported web forgeries".

• Delete all files beginning with urlclassifier in your profile folder (~/.mozilla/firefox/<profile_dir>/):

$ rm -i ~/.mozilla/firefox/<profile_dir>/urlclassifier*

Some of these files might be recreated by Firefox, but they won't grow any larger than their initial size.

Stop urlclassifier3.sqlite from being created again

If you did remove all the urlclassifier* files as mentioned above, you may find out that urlclassifier3.sqlite keeps growing again after a certain time. Here is a simple solution to avoid it for now and ever.

$ cd ~/.mozilla/firefox/<profile_dir>
$ echo "" > urlclassifier3.sqlite
$ chmod 400 urlclassifier3.sqlite

This effectively makes the file empty and then read-only so Firefox cannot write to it anymore.

Turn off OCSP validation

The OCSP validation of Firefox may cause Firefox to become slow every time a HTTPS connections to a new site is done (see this article for details). This may be particularly bad in recent times where web gadgets are included in pages via HTTPS (the "like" buttons of the social networks for example) resulting in many HTTPS connections for a single URL loaded.

• Turn off the following option under the advanced tab in preferences -> Encryption -> Validation: "Use the Online Certificate Status Protocol (OCSP) to confirm the current validity of certificates".

Turn off the disk cache

Every object loaded (html pages, jpeg images, css stylesheets, gif banners) is saved in the Firefox cache, to be loaded in the future without to download it again from the server, but only fraction of these objects will be really reused without download (usually the 30%). This because of too short expiration times for the objects, updates or simply the user behavior (to load new pages instead the ones already visited). The Firefox cache is divided in memory and disk cache and using the disk cache results to frequent disk writes, because every time an object loaded it is written to the disk and some older object is removed.

• Turn on the following option under the advanced tab in preferences -> Network -> Validation: "Override automatic cache management" and specify zero in "Limit cache to".

Longer interval to save session

The Firefox session store automatically saves the current status (opened urls, cookies, history and bookmarks) to the disk every 15 seconds. It may be too frequent for the user needs, resulting in a frenquet disk access.

This setting can be found on the about:config page (try searching for sessionstore).

• browser.sessionstore.interval 300000

Other modifications

This section contains some other modifications that may increase Firefox's performance.

Reduce load time by compressing the Firefox binary with UPX

UPX is an executable packer that supports very fast decompression and induces no memory overhead. It can be installed with the upx package, availalble in the official repositories.

Before using upx to compress the Firefox executable, make a backup of the binary:

# cp /usr/lib/firefox/firefox /usr/lib/firefox/firefox.backup

Finally, invoke upx, applying the best possible compression level:

# upx --best /usr/lib/firefox/firefox

Defragment the profile's SQLite databases

Warning: This procedure may damage the databases in such a way that sessions are not saved properly.

In Firefox 3.0, bookmarks, history, passwords are kept in an SQLite databases. SQLite databases become fragmented over time and empty spaces appear all around. But, since there are no managing processes checking and optimizing the database, these factors eventually result in a performance hit. A good way to improve start-up and some other bookmarks and history related tasks is to defragment and trim unused space from these databases.

profile-cleaner^AUR in the AUR does just this.

Sample size differences comparison

SQLite database	Size Before	Size After	% change
urlclassifier3.sqlite	37 M	30 M	19 %
places.sqlite	16 M	2.4 M	85 %

Cache the entire profile into RAM via tmpfs

If the system has memory to spare, tmpfs can be used to cache the entire profile directory, which might result in increased Firefox responsiveness.

Appearance

Fonts

Configure the DPI value

Modifying the following value can help improve the way fonts looks in Firefox if the system's DPI is below 96. Firefox, by default, uses 96 and only uses the system's DPI if it is a higher value. To force the system's DPI regardless of its value, type about:config into the address bar and set layout.css.dpi to 0.

Note that the above method only affects the Firefox user interface's DPI settings. Web page contents still use a DPI value of 96, which may look ugly or, in the case of high-resolution displays, may be rendered too small to read. A solution is to change layout.css.devPixelsPerPx to system's DPI divided by 96. For example, if your system's DPI is 144, then the value to add is 144/96 = 1.5. Changing layout.css.devPixelsPerPx to 1.5 makes web page contents use a DPI of 144, which looks much better.

Default font settings from Microsoft Windows

Below are the default font preferences when Firefox is installed in Microsoft Windows. Many web sites use the Microsoft fonts.

Proportional: Serif Size (pixels): 16
Serif: Times New Roman
Sans-serif: Arial
Monospace: Courier New Size (pixels): 13

General user interface CSS settings

Firefox's user interface can be modified by editing the userChrome.css and userContent.css files in ~/.mozilla/firefox/<profile_dir>/chrome/ (profile_dir is of the form hash.name, where the hash is an 8 character, seemingly random string and the profile name is usually default).

Note: The chrome/ folder and userChrome.css/userContent.css files may not necessarily exist, so you have to create them.

This section only deals with the userChrome.css file which modifies Firefox's user interface, and not web pages.

Change the font

The setting effectively overrides the global GTK+ font preferences, and does not affect webpages, only the user interface itself:

~/.mozilla/firefox/<profile_dir>/chrome/userChrome.css

* {
    font-family: "FONT_NAME";
}

Hide button icons

Enables text-only buttons:

~/.mozilla/firefox/<profile_dir>/chrome/userChrome.css

.button-box .button-icon {
    display: none;
}

Hiding various tab buttons

These settings hide the arrows that appear to the horizontal edges of the tab bar, the button that toggles the "all tabs" drop-down list, and the plus sign button that creates a new tab.

~/.mozilla/firefox/<profile_dir>/chrome/userChrome.css

/* Tab bar */

.tabbrowser-strip *[class^="scrollbutton"] {
    /* Hide tab scroll buttons */
    display: none;
}

.tabbrowser-strip *[class^="tabs-alltabs"] {
    /* Hide tab drop-down list */
    display: none;
}

.tabbrowser-strip *[class^="tabs-newtab-button"] {
    /* Hide new-tab button */
    display: none;
}

Horizontal tabs

To place the tab bar horizontally stacked along the sides of the browser window:

~/.mozilla/firefox/<profile_dir>/chrome/userChrome.css

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

.tabbrowser-strip {
    -moz-box-orient: vertical;
    /*
     * 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;
}

Auto-hide Bookmarks Toolbar

~/.mozilla/firefox/<profile_dir>/chrome/userChrome.css

#PersonalToolbar {
    visibility: collapse !important;
}

#navigator-toolbox:hover > #PersonalToolbar {
    visibility: visible !important;
}

Remove sidebar width restrictions

~/.mozilla/firefox/<profile_dir>/chrome/userChrome.css

/* remove maximum/minimum  width restriction of sidebar */
#sidebar {
    max-width: none !important;
    min-width: 0px !important;
}

Web content CSS settings

This section deals with the userContent.css files in which you can add custom CSS rules for web content. You can import other CSS files by adding to the file:

~/.mozilla/firefox/<profile_dir>/chrome/userContent.css

@import url("./imports/some_file.css");

Block certain parts of a domain

~/.mozilla/firefox/<profile_dir>/chrome/userContent.css

@-moz-document domain(example.com) {
    div#header {
        background-image: none !important;
    } 
}

Add [pdf] after links to PDF files

~/.mozilla/firefox/<profile_dir>/chrome/userContent.css

/* add '[pdf]' next to links to PDF files */
a[href$=".pdf"]:after {
    font-size: smaller;
    content: " [pdf]";
}

Show URLs at the bottom of the screen when hovering a link

~/.mozilla/firefox/<profile_dir>/chrome/userContent.css

a[href]:hover {
    text-decoration: none !important;
}

a[href]:hover:after {
    content: attr(href);
    position: fixed; left: 0px; bottom: 0px;
    padding: 0 2px !important;
    max-width: 95%; overflow: hidden;
    white-space: nowrap; text-overflow: ellipsis;
    font:10pt sans-serif !important;
    background-color: black  !important;
    color: white !important;
    opacity: 0.7;
    z-index: 9999;
}

Firefox 4 New Menu Bar/Firefox Button

To toggle between the new Firefox button and the classic menu bar:

• if the button is active, check Preferences > Menu Bar, or right click in the toolbar area and check Menu Bar.
• if the menu bar is active, uncheck View > Toolbars > Menu Bar, or right click in the toolbar area and uncheck Menu Bar.

In GNU/Linux, you will just get a plain grey button instead of the new orange one from Windows. However you can change this to either a Firefox icon or the icon followed by the "Firefox" text.

Adding the following to your ~/.mozilla/firefox/userprofile/chrome/userChrome.css file will place the icon before the text:

#appmenu-toolbar-button {
  list-style-image: url("chrome://branding/content/icon16.png");
}

Adding the following to the same file will remove the "Firefox" text:

#appmenu-toolbar-button > .toolbarbutton-text,
#appmenu-toolbar-button > .toolbarbutton-menu-dropmarker {
  display: none !important;
}

This userChrome.css configuration copies the default Windows Firefox 4+ look and adds an orange background to the button, with a purple background in Private Browsing mode:

#main-window:not([privatebrowsingmode]) #appmenu-toolbar-button {
    -moz-appearance: none !important;
    color: #FEEDFC !important;
    background: -moz-linear-gradient(hsl(34,85%,60%), hsl(26,72%,53%) 95%) !important;
    border: 1px solid #000000 !important;
}

#main-window:not([privatebrowsingmode]) #appmenu-toolbar-button:hover:not(:active):not([open]) {
    -moz-appearance: none !important;
    color: #FEEDFC !important;
    background: -moz-linear-gradient(hsl(26,72%,53%), hsl(34,85%,60%) 95%) !important;
    border: 1px solid #000000 !important;
}


#main-window:not([privatebrowsingmode]) #appmenu-toolbar-button:hover:active,
#main-window:not([privatebrowsingmode]) #appmenu-toolbar-button[open] {
    -moz-appearance: none !important;
    color: #FEEDFC !important;
    background: -moz-linear-gradient(hsl(26,72%,53%), hsl(26,72%,53%) 95%) !important;
    border: 1px solid #000000 !important;
}

#appmenu-toolbar-button {
    -moz-appearance: none !important;
    color: #FEEDFC !important;
    background: -moz-linear-gradient(hsl(279,70%,46%), hsl(276,75%,38%) 95%) !important;
    border: 1px solid #000000 !important;
}


#main-window #appmenu-toolbar-button:hover:not(:active):not([open]) {
    -moz-appearance: none !important;
    color: #FEEDFC !important;
    background: -moz-linear-gradient(hsl(276,75%,38%), hsl(279,70%,46%) 95%) !important;
    border: 1px solid #000000 !important;
}


#main-window #appmenu-toolbar-button:hover:active,
#main-window #appmenu-toolbar-button[open] {
    -moz-appearance: none !important;
    color: #FEEDFC !important;
    background: -moz-linear-gradient(hsl(276,75%,38%), hsl(276,75%,38%) 95%) !important;
    border: 1px solid #000000 !important;
}

Note: You need to create both the chrome directory and userChrome.css, if they do not already exist.

Block ads

See floppymoose.com for an example of how to use userContent.css as a basic ad-blocker.

Miscellaneous

Other tips and tweaks.

Mouse wheel scroll speed

To modify the default values (i.e. speed-up) of the mouse wheel scroll speed, go to about:config and search for mousewheel.acceleration. This will show the available options, modifying the following:

• Set mousewheel.acceleration.start to -1.
• Set mousewheel.acceleration.factor to the desired number (10 to 20 are common values).

Alternatively you can install the SmoothWheel add-on.

Change the order of search engines in the Firefox Search Bar

To change the order search engines are displayed in:

• Open the drop-down list of search engines and click Manage Search Engines... entry.
• Highlight the engine you want to move and use Move Up or Move Down to move it. Alternatively, you can use drag-and-drop.

How to open a *.doc automatically with Abiword or LibreOffice Writer

Go to Preferences > Applications and search for Word Document (or Word 2007 Document for *.docx). After finding it, click the drop-down list and select Use other.... From there you have to specify the exact path to the Abiword or Writer executable (i.e./usr/bin/abiword or /usr/bin/lowriter).

"I'm Feeling Lucky" mode

Some search engines have a feeling lucky feature. For example Google has "I'm Feeling Lucky" and DuckDuckGo has "I'm Feeling Ducky".

To activate them:

1. Type about:config in the address bar.
2. Search for the string keyword.url.
3. Modify its value (if any) to the URL of the search engine.

For Google, set it to:

http://www.google.com/search?btnI=I%27m+Feeling+Lucky&q=

For DuckDuckGo, set it to:

https://duckduckgo.com/?q=\

For Google Encrypted (RCA-4 128bit High security encyption), set it to:

https://encrypted.google.com/search?btnI=I%27m+Feeling+Lucky&q=

Secure DNS with DNSSEC validator

You can enable DNSSEC support for safer browsing.

Adding magnet protocol association

In about:config set network.protocol-handler.expose.magnet to false.

The next time you open a magnet link, you will be prompted with a Launch Application dialogue. From there simply select your chosen torrent client. This technique can also be used with other protocols.

Prevent accidental closing

The Disable Ctrl-Q Shortcut extension can be installed to prevent unwanted closing of the browser.

An alternative is to add a rule in your window manager configuration file. For example in openbox add:

 <keybind key="C-q">
   <action name="Execute">
     <execute>false</execute>
   </action>
 </keybind>

in the <keyboard> section of your rc.xml file.

Note: This will be effective for every application used under a graphic server.

Plugins don't work with latest version

Due to Arch's bleeding edge nature, there can be some compatility issues with plugins not working with the latest Firefox install (ie Pentadactyl). If possible, try installing the nightly/beta builds available, or see Downgrading Packages.

See also

• MozillaZine Wiki
• about:config Entries Explained
• Top Fox: Completing the Feel of Firefox
• Firefox: Defining font type and size