# 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

OCSP validation may cause Firefox to become slower for each (HTTPS) connection to a new server. This is worse, recently, where web gadgets are included in pages via HTTPS (e.g., "like" buttons of the social networks), resulting in many connections for a single URL.

- Turn off the following option under Preferences -> Advanced -> Certificates -> Validation: "Use the Online Certificate Status Protocol (OCSP) to confirm the current validity of certificates".

Warning: Disabling OCSP causes vulnerabilities to man-in-the-middle attacks. If you are using a potentially vulnerable connection such as Wifi or VPN, it is strongly advised to leave OCSP on.

#### 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 frequent disk access.

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

- browser.sessionstore.interval 300000

#### Immediate rendering of pages

Mozilla applications render web pages incrementally - they display what's been received of a page before the entire page has been downloaded. Since the start of a web page normally doesn't have much useful information to display, Mozilla applications will wait a short interval before first rendering a page. This preference controls that interval. Note that if you are on slower connections (dial up) changing this setting might make web pages load for longer times even though the page appears faster.

This setting can be created in the `about:config` page as

- nglayout.initialpaint.delay with a value of 0.

### 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 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

See the main article: Font configuration

#### 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 they may need to be created.

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` file in which you can add custom CSS rules for web content. Changes to this file will take effect once the browser is restarted.

This file can be used for making small fixes or to apply personal styles to frequently visited websites. Custom stylesheets for popular websites are available from sources such as userstyles.org. You can install an add-on such as superUserContent to manage themes. This add-on creates the directory `chrome/userContent.css.d` and applies changes to the CSS files therein when the page is refreshed.

#### Import other CSS files

    ~/.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:

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

For DuckDuckGo, set it to:

    https://duckduckgo.com/?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 compatibility issues with plugins not working with the latest Firefox install (e.g. Pentadactyl). If possible, try installing the nightly/beta builds available, or see Downgrading packages.

Disable Add-on Compatibility Checks plugin should take care of spurious compatibility issues when the plugins get disabled, even though they work just fine with the new version.

### Make it flow smoothly (not jerky & choppy)

Firefox can be 'jerky' of 'choppy' on the screen. This post on MozillaZine gives settings that work on Gentoo, but they work for me on Arch as well.

1. Set `mousewheel.min_line_scroll_amount` to 40
2. Set `general.smoothScroll` and `general.smoothScroll.pages` to false
3. Set `image.mem.min_discard_timeout_ms` to something really large. Like 2100000000 or 80000000000000.
4. Set `image.mem.max_decoded_image_kb` to at least 512K

Now scrolling should flow smoothly.

## See also

- MozillaZine Wiki
- about:config Entries Explained
- Firefox tuneup: configuration necessities
- Firefox: Defining font type and size

Category:

- Web Browser