Hacking Firefox: Definitive guide to secrets of about:config

You may have installed countless add-on in Firefox to enhance yourusing experience, but if you want to get the most out of Firefox, youreally have to hack your way into the about:config.
The about:config page contains most (if not, all) ofFirefox configuration options. It is so far the most effective, and themost powerful way to tweak and enhance your Firefox performance. Hereare 28 of the popular tweaks.

Accessing your about:config page
In your Firefox, type about:config in the address bar.

You will be shown a warning page. Click the �I�ll be careful, I promise!� button to proceed.

On the main page, you will see a long list of configuration entries. Enter the name of the key you want to update in the �Filter� field. The list will narrow to only the entries that match your keyword as you type.
To modify the value, simply double click on the entry value field and update the entry. That�s all!
Isn�t that simple? Now, let�s get to the tweaking.
1) Adjust the Smart Location Bar�s Number of Suggestions
In Firefox 3, when you start typing in the location bar, a drop-downlist of suggestion URLs will be shown. If you want it to show more than12 suggestions (12 is the default), you can adjust the browser.urlbar.maxRichResults keys and get it to show the number you want.

Config name: browser.urlbar.maxRichResults
Default: 12
Modified value: Set to your desired number of suggestion. If you want to disable it all together, set it to -1
2) Disable the session restore function
Firefox 3 automatically saves your session every 10 secs so thatwhenever it crashes, it can restore all your tabs. While this is auseful feature, some of you might find it irritating. To disable thisfunction, toggle the value of browser.sessionstore.enabled to False
Config name: browser.sessionstore.enabled
Default: True
Modified value: False if you want to disable the session restore function
3) Adjust the Session Restore Saving Frequency
Same as above, if you decided to keep the session restore featureon, but want to reduce the session saving frequency, change the valueof browser.sessionstore.interval so that Firefox will save the session at a longer interval.
Config name: browser.sessionstore.interval
Default: 10000 (in msecs, equivalent to 10secs)
Modified value: Set it to your desired value. 1000 means 1 sec and 60000 means 1 minute.
4) Enable Advanced Color Profile Support
Firefox has this advanced color profile features that display higherimage quality. It is not enabled by default as it has a negative effecton the performance of the browser. If you are concern with the imagequality rather than the performance, you can activated it via the gfx.color_management.enabled setting
Config name: gfx.color_management.enabled
Default: False
Modified value: True (if you want to activate the color profile support feature)
5) Disable Antivirus Scanning
This is mainly for Windows users. By default, Firefox 3automatically scan the downloaded file with the default anti-virusapplication to make sure it is free of virus. If you download a bigfile, it could take a long time for the whole scanning process tocomplete. To increase the performance of the browser, you might want toconsider disabling the anti-virus scanning via the browser.download.manager.scanWhenDone key.
Config name: browser.download.manager.scanWhenDone
Default: True
Modified value: False (if you want to disable it)
6) Configuring The Scrolling Tabs
When you opened many tabs, Firefox will not keep on reducing the tabwidth. Instead, it shows a scrolling bar so that the min width (100px)is conserved and you can scroll to find your tabs. If you are those whodon�t like the scrolling tab function and prefer Firefox to show allthe tabs, regardless how small it is, you can set the value of browser.tabs.tabMinWidthto 0 to disable it. Similarly, if you want Firefox to display more tabsbefore showing the scrolling button, you can reduce the default valueto a lower value, say 75 pixels.

Config name: browser.tabs.tabMinWidth
Default: 100
Modified value: 0 if you want to disable the scrolling functions, other values to set the min width value
7) Show/Disable Close button on Tabs
Some people love to see the Close (the red X) button on every tabs, but some hate it. Whatever is it, you can configure it to your preferences via the browser.tabs.closeButtons setting.

Config name: browser.tabs.closeButtons
Default: 1
Modified values:

0 � display a close button on the active tab only
1- display close buttons on all tabs
2- don�t display any close buttons
3- display a single close button at the end of the tab strip

Extend Scripts Execution Time
In Firefox 3, a script is only given 10 seconds to respond, afterwhich it will issue a unresponsive script warning. If you are hooked ona slow network connection, you might want to increase the scriptexecution time via dom.max_script_run_time to cut down on the frequency of the no script warning.
Config name: dom.max_script_run_time
Default:10 (in secs)
Modified value: 20, or any values greater than 10
9) Handling JavaScript Popups
When you come across a site that executes a javascript open newwindow function, and if the popup window is without all the usualwindow features, i.e. back/forward/reload buttons, status bar etc,Firefox will automatically treat it as a popup and will not open it asa new tab. However, if you find this to be a nuisance and wanted toopen all new windows in a new tabs, you can specify it via the browser.link.open_newwindow.restriction setting.
Config name: browser.link.open_newwindow.restriction
Default: 2� Open all JavaScript windows the same way as you have Firefox handlenew windows unless the JavaScript call specifies how to display thewindow
Modified values:

0 � open all links as how you have Firefox handle new windows
1 � do not open any new windows
2- open all links as how you have Firefox handle new windows unless the Javascript specify how to display the window

10) Enable Spell Checking In All Text Fields
The default spell checking function only checks for multi-line textboxes. You can get it to spell-check for single line text box as well.
Config name: layout.spellcheckDefault
Default: 1 (spell checker for multi-lines text boxes only)
Modified values:

0 � disable the spell checker
2 � enable the spell checker for all text boxes

11) Open Search Box Results In New Tab
When you search using the search box at the top right hand corner ofthe browser, it will display the search results in the current tab. Ifyou don�t want the search to interfere with your current tab, you cantweak the browser.search.openintab to make it open in a new tab.
Config Name: browser.search.openintab
Default: False
Modified value: True (open search box results in new tab)
12) Lower The Physical Memory Used When Minimized
This tweak is mainly for Windows users. When you minimize Firefox,it will send Firefox to your virtual memory and free up your physicalmemory for other programs to use. Firefox will reduce its physicalmemory usage, when minimized, to approximately 10MB (give or take some)and when you maximize Firefox it will take back the memory that itneeds.
The preference name does not exist and needs to be created.
Right click on the background and select New->Boolean.
Enter the name when prompted: config.trim_on_minimize
Enter the values: True
13) Speed up your Firefox
Several tweaks required for this
Config name: network.http.pipelining
Default: False
Modified value: True
Config name: network.http.proxy.pipelining
Default: False
Modified value: True
Config name: network.http.pipelining.maxrequests
Default: 4
Modified value: any value higher than 4, but not more than 8
Config name: network.http.max-connections
Default: 30
Modified value: 96
Config name: network.http.max-connections-per-server
Default: 15
Modified value: 32
14) Increase/Decrease the Amount of Disk Cache
When a page is loaded, Firefox will cache it into the hard disk sothat it doesn�t need to be download again for redisplaying. The biggerthe storage size you cater for Firefox, the more pages it can cache.
Before you increase the disk cache size, make sure that ~~browser.cache.disk.enabled~~ browser.cache.disk.enable is set to True.
Config name: browser.cache.disk.capacity
Default: 50000 (in KB)
Modified value:

0 � disable disk caching
any value lower than 50000 reduces the disk cache
any value higher than 50000 increases the disk cache.

15) Select all text when click on the URL bar
In Windows and Mac, Firefox highlights all text when you click onthe URL bar. In Linux, it does not select all the text. Instead, itplaces the cursor at the insertion point. Regardless which platform youare using, you can now tweak it to either select all or place cursor at insertion point.

Config name: browser.urlbar.clickSelectsAll
Modified value:

False � place cursor at insertion point
True � select all text on click

16) Autofill Address in URL Bar
Other than the smart location feature, you can also get your URL bar to autofill the address as you type the URL.

Config name: browser.urlbar.autofill
Default: False
Modified value: True (Have Firefox autofill the address as you type in the URL bar)
17) Same Zoom Level For Every Site
Firefox remembers your zoom preference for each site and set it toyour preferences whenever you load the page. If you want the zoom levelto be consistent from site to site, you can toggle the value of browser.zoom.siteSpecific from True to False.
Config name: browser.zoom.siteSpecific
Default: True
Modified value: False (enable same zoom preferences for every sites)
1 Setting your zoom limit
If you find that the max/min zoom level is still not sufficient foryour viewing, you can change the zoom limit to suit your viewing habits.
Config name: zoom.maxPercent
Default: 300 (percent)
Modified value: any value higher than 300
Config name: zoom.minPercent
Default: 30 (percent)
value: any value
19) Configure Your Backspace Button
In Firefox, you can set your backspace to better use by getting it to either go back to the previous page or act as page up function.
Config name: browser.backspace_action
Default: 2 (does nothing)
Modified value:

0 � go back previous page
1- page up

20) Increase Offline Cache
If you do not have access to Internet most of the time, you mightwant to increase the offline cache so that you can continue to workoffline. By default, Firefox 3 caches 500MB of data from supportedoffline Web apps. You can change that value to whatever amount of yourchoice.
Config name: browser.cache.offline.capacity
Default: 512000 (in KB)
Modified value: any value higher than 512000 will increase the cache value
21) Auto Export Firefox 3 bookmarks to bookmarks.html
Unlike the previous version, Firefox 3 backup the bookmarks file in places.sqlite rather than the usual bookmarks.html. Since bookmarks.htmlallows us to export and sync our bookmarks with other browser, it willbe very useful if Firefox 3 can backup the bookmark to the bookmarks.html as well.
Config name: browser.bookmarks.autoExportHTML
Default: False
Modified value: True (auto export bookmarks file to bookmarks.html)
22) Disable Extension Compatibility Checks
This is useful if you want to use an extension that is not supportedby your version of Firefox badly. It is not recommended, but you canstill do it at your own risk.
Right click and select New->Boolean. Enter extensions.checkCompatibility in the field. Enter False in the next field.
Right click again and select New->Boolean. Enter extensions.checkUpdateSecurity into the field and enter False into the next field.
23) Disable Delay Time When Installing Add-on
Everytime you wanted to install a Firefox add-on, you will have towait for several secs before the actual installation starts. If you aretired of waiting, you can turn the function security.dialog_enable_delay off so that the installation will start immediately upon clicking.

Config name: security.dialog_enable_delay
Default: 2000 (in msec)
Modified value:

0 � start installation immediately
any other value (in msec)

24) View Source in Your Favorite Editor
This is very useful for developers who are always using the �view source� function. This tweak allows you to view the source code in an external editor.
There are two configuration need to be made:
Config name: view_source.editor.external
Default: False
Modified value: True ( enable view source using external text editor)
Config name: view_source.editor.path
Default: blank
Modified value: insert the file path to your editor here.
25) Increasing �Save Link As� timeout value
When you right click and select the �Save Link As��, thebrowser will request the content disposition header from the URL so asto determine the filename. If the URL did not deliver the header within1 sec, Firefox will issue a timeout value. This could happen veryfrequently in a slow network connection environment. To prevent thisissue from happening frequently, you can increase the timeout value soas to reduce the possibility of a timeout.
Config name: Browser.download.saveLinkAsFilenameTimeout
Default: 1000 (1 sec)
Modified value: any value higher than 1000 (value is in msec)
26) Animate Fullscreen Toolbar Collapse mode
In Firefox�s fullscreen mode, toolbars and the tab strip are hiddenat the top of the screen and only shown on mouseover. To draw attentionto this, there is an animation of the toolbar sliding upwards andoff-screen when fullscreen mode is toggled on. For performance issue,the animation of the collapse of the toolbar only appear for the firsttime. For some reason that you may love/hate the animation, you canadjust Browser.fullscreen.animateUp to switch it on/off for every collapse.
Config name: Browser.fullscreen.animateUp
Default: 1 (animate the toolbar collapse only the first time)
Modified value:

0 -disable the animation
2- enable the animation for every collapse

27) Autohide Toolbar in Fullscreen mode
In fullscreen mode, the toolbar is set to autohide and appear uponmouseover. If you have a need to view the toolbar at all time, you cantoggle the value of browser.fullscreen.autohide to False to always show the toolbar.
Config name: browser.fullscreen.autohide
Default: True (always autohide)
Modified value: False (always show the toolbar)
2 Increase Add-On search result
If you go to Tools->Add-ons->Get Add-ons and performa search there, Firefox will only fetch and display 5 matching results.If you want Firefox to show more than 5 results (say 10), you canadjust extensions.getAddons.maxResults to get it to display more results.
Config name: extensions.getAddons.maxResults
Default: 5
Modified value: any value more than 5
This list of about:config is definitely not the complete list. If you have any tricks not listed here, please add it in the comment.

1: Speed up Firefox
This hack requires a few steps. Search for pipelining in the filter and you should see:
network.http.pipelining: Change this to true.
network.http.proxy.pipelining: Change this to true.
network.http.pipelining.maxrequests: Change this to 8.
Now search for max-connections and you should see:
network.http.max-connections: Change this to 96.
network.http.max-connections-per-server: Change this to 32.
2: Disable antivirus scanning
This is only for the Windows version. If you�re downloading largefiles, this scanning can seriously slow things down. And since you willmost likely scan the downloaded file anyway, you�ll probably want todisable this. Of course, if you are uber paranoid (not a bad trait forcomputing), you might want to leave this entry alone.
To disable antivirus scanning, search for scanWhenDone and you should see:
browser.download.manager.scanWhenDone: Change this to false.
3: Open Javascript popups as tabs
If a popup window lacks the features of a browser window, Firefoxwill handle it like a popup. If you would prefer to open all windows,including popups, as new tabs, you need to tell Firefox inabout:config. Search for newwindow and you will see three entries. Of those three entries, you will want to modify:
browser.link.open_newwindow.restriction: Change this to 0.
4: Spell checking in all fields
By default, Firefox checks spelling only in multiple-line textboxes. You can set it to check spelling in all text boxes. Search for spellcheckdefault and you should see:
layout.spellcheckDefault: Change this to 2.
5: Open search bar results in new tab
When you use the search bar, the results display in the current tab.This can be a nuisance because you will navigate out of the page youare currently in. To make sure Firefox always opens search results in anew tab, search for openintab and you should see:
browser.search.openintab: Change this to true.
6: Auto export bookmarks
In Firefox 3, bookmarks are automatically saved and exported foryou. The only problem is that by default, they�re saved asplaces.sqlite instead of the more convenient bookmarks.html. To changethis setting so that they can be easily re-imported, search for autoExportHTML and you should see:
browser.bookmarks.autoExportHTML: Change this to true.
7: Disable extension install delay
One of the few gripes I have with Firefox is the silly countdown youmust endure every time you want to install an extension. Fortunately,this can be disabled. Search for enable_delay and you should see:
security.dialog_enable_delay: Change this to 0.
8: View source code in an external editor
When you need to view the source of a page, it opens up in browserpopup. Most developers would probably like to have that opened in theirfavorite editor instead of having to cut and paset. To do this, thereare two entries to modify. Search for view_source.editor and you will see:
view_source.editor.external: Change this to true.
view_source.editor.path: Change this to the explicit path to your editor of choice.
9: Get more add-on search results
When you do a search in the Add-on window, you�ll see just fiveresults. You might find it more efficient to increase this number.Search for getAddons and you should see:
extension.getAddons.maxResults: Change this to 10 (or higher, if you want to see even more).
10: Redefine the Backspace button
Did you know you can configure Firefox to use the backspace buttonto either go back a page or go up a page? This keeps power users fromhaving to go back and forth from the keyboard to the mouse. Search for backspace and you will see:
browser.backspace_action: Change this to 0 for previous page and 1 for page up.
Your turn
Do you have other favorite hacks you�ve discovered that make Firefox even more useful? If so, share them below.

Firefox 3 about:config file isthe core configuration file of Firefox. By editing about:config file wecan get amazing hacks for Firefox 3. Firefox allows the users to changemany preferences in the about:config file so it�s totally ethical to doit.Here is list of 21 Firefox 3 hacks & tweaks.

To get the Firefox 3 configuration file type �about:config� at address bar.

Here is List of about:config hacks for Firefox 3

1) Disable Extension Compatibility Checks
extensions.checkCompatibility = False
extensions.checkUpdateSecurity = False

2) Location Bar (Set number Auto Complete URL at Address Bar)

This is a good hack to trim down that huge auto-complete list on your URL bar. By default it displays maximum 12 URL
browser.urlbar.maxRichResults = #
Enter Number at # (3,10,12 etc)

3) Stop Displaying Website Icon (Favicon) in Address bar & On Tab
browser.chrome.site_icons = False

4) Disable Prefetch (Helpful for frequent Google searcher, low-speed internet connection or low RAM)
network.prefetch-next = False

5) Extend Spell check to forms
layout.spellcheckDefault = 2
Change Value from 1 to 2

6) Disable Blinking Text
browser.blink_allowed = False

7) Speed Tweaks
network.http.pipelining false to true
network.http.pipelining.maxrequests 30 to 8
network.http.max-connections 30 to 96
network.http.max-connections-per-server 15 to 32
network.http.max-persistent-connections-per-server 6 to 8
network.http.pipelining.ssl false to true
network.http.proxy.pipelining false to true

8 ) Disable Annoying Browser Behavior

dom.disable_window_open_feature.menubar
dom.disable_window_move_resize
dom.disable_window_open_feature.titlebar
dom.disable_window_open_feature.toolbar
Set all of above to value False

9) Remove Tab Close Button from all Tab and set A single Close Button at Right

browser.tabs.closeButtons = 3
Single Close Button to control all Firefox Opened Tabs. (value should be 3 and not 2 Thanks Andreas )

10) Disabler Browser Toolbar Tip
browser.chrome.toolbar_tips = False

11) Show More Tabs on Single Firefox Window before Scrolling
browser.tabs.tabMinWidth = 75
Setting lesser value with reduce Tab width

12) Past Copy Content with Middlemouse Click
middlemouse.paste = True

13) Scroll webpage in One Go

mousewheel.withaltkey.action=1

14) Disable Delay Time While Installing Firefox Add-on

security.dialog_enable_delay = 0

(Zero is number of seconds Firefox should wait while installing Add-on)

15) Increase History Undo Close Tab Limit ( Recently Closed Tabs )

browser.sessionstore.max_tabs_undo=15

By default you can undo 10 recently closedtabs inorder to increase your history closed tabs. Change number 13 toas per your choice.

16) Open Firefox Default Search Bar Result in New Tab

browser.search.openintab=True

17) Right Click View Source in Your Favorite Editor

view_source.editor.external=True
view_source.editor.path= Path of Editor

(e.g. path C:\Program Files\npp.4.8.2.bin\notepad++.exe)

1 Enable/Disable Single Click to Select Whole URL in Address bar

To Enable Single Click Select URL of address bar use the below about:config Tweak

browser.urlbar.clickSelectsAll = True
To disable Single Click Select

browser.urlbar.clickSelectsAll = False

19) Emule/ed2k link association (Linux users)
network.protocol-handler.app.ed2k= /usr/bin/ed2k
network.protocol-handler.external.ed2k = true

20) Fast Scrolling Across Tabs

toolkit.scrollbox.scrollIncrement =75
( 75 is number of pixels to scroll at a time when scrolling the tab strip�s scrollbox. (Default: 20)

21) Auto Complete URL while You type at address Bar

browser.urlbar.autoFill=True

Many of above about:config hacks areavailable in Older Firefox Version, at the end if some thing goes wrongthen feel free to restore your about:config to older setting see thebelow image of how to restore about:config

Hope you guys like this Firefox 3 hacks,
If you have any tips or hacks related to Firefox 3 about:config, hacks, tweaks do let me know I will include it in above list.

Speed tweaks:
content.interrupt.parsing=true
content.max.tokenizing.time[integer]=3000000
content.maxtextrun[integer]=8191
content.notify.backoffcount[integer]=200
content.notify.interval[integer]=100000
content.notify.ontimer=true
content.notify.threshold[integer]=100000
content.switch.threshold[integer]=650000
network.dnsCacheEntries[integer]=256
network.dnsCacheExpiration[integer]=86400
network.ftp.idleConnectionTimeout[integer]=60
network.http.keep-alive.timeout[integer]=30
network.http.max-persistent-connections-per-proxy[integer]=24
network.http.pipelining.firstrequest=true
nglayout.initialpaint.delay[string]=0