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10 handy Firefox about:config hacks

If you really want to fine-tune your Firefox functionality, you have to roll up your sleeves and tinker with the about:config page. Jack Wallen shares some simple hacks to make Firefox work the way you want.

Unless you're a Firefox power user, you may not be familiar with the about:config page. The Firefox about:config page is not so much a page as it is a somewhat hidden configuration section. It's hidden because it's fairly powerful and not nearly as simple to use as the standard Preferences window. In the about:config page, you have to know what you are doing or you can mess things up a bit. In fact, when you attempt to go to that page for the first time, you have to accept an agreement (which is really just a warning) before you can continue.

How this page works is simple. You reach the page by entering about:config in the address bar. There are entries (one per line) that handle various types of configurations. Each entry has a searchable keyword. The entries can be of Boolean, integer, or string value. Entries contain Name, Status, Type, and Value. Typically, you will be modifying only the Value, by double-clicking on it and making the change. With all of that in mind, let's take a look at 10 of the best ways you can "hack" the about:config page.

Note: This article is also available as a PDF download.


Tip

If Firefox is fubar'd because you accidentally misconfigured about:config, you can fix it in one of two ways:

  • Make a backup of your prefs.js file before you start editing. Then, if something goes wrong, you can restore it by copying it over the corrupt file.
  • If you can't restore via a backup prefs.js file, you can exit Firefox and issue the command firefox -safe-mode to bring up the Firefox Safe Mode screen. Then, just select Reset All User Preferences To Firefox Defaults. Note: This will restore all user preferences to their default values.


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 large files, this scanning can seriously slow things down. And since you will most likely scan the downloaded file anyway, you'll probably want to disable this. Of course, if you are uber paranoid (not a bad trait for computing), 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, Firefox will handle it like a popup. If you would prefer to open all windows, including popups, as new tabs, you need to tell Firefox in about: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 text boxes. 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 you are currently in. To make sure Firefox always opens search results in a new 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 for you. The only problem is that by default, they're saved as places.sqlite instead of the more convenient bookmarks.html. To change this 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 you must 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 browser popup. Most developers would probably like to have that opened in their favorite editor instead of having to cut and paset. To do this, there are 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 five results. 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 button to either go back a page or go up a page? This keeps power users from having 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.


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About

Jack Wallen is an award-winning writer for TechRepublic and Linux.com. He’s an avid promoter of open source and the voice of The Android Expert. For more news about Jack Wallen, visit his website getjackd.net.

54 comments
ops
ops

Given that this article dates back to 2009, now that we are on version 15.0.1 do these tweeks still fully apply?

jbleahy
jbleahy

Nice hacks. One is mispelled: extension.getAddons.maxResults, should be plural: extensions.getAddons.maxResults

Rob C
Rob C

Would the 'Moderators' of this site (or the author of this article), please get the site designers to BLANK OUT THE SUBJECT BOX, when we are adding Comments. Most idiots (including me) don't think to enter a meaningful Subject, as there is already something present If it is blank, the page can refuse to accept the comment until we put something there. I don't know about you guys, but I am sure as hades, not going to click on every post, that is lacking a meaningful Subject, to see if I am interested in that comment.

blamenixon
blamenixon

C:\Users\(your name)\AppData\Roaming\Mozilla\Firefox\Profiles\as4a9x4p.default took me a minute, but I've been looking for a way to revert back at times after some mindless tweaking late at night.

nottheusual1
nottheusual1

Firefox 3.5.5 on Win 7 wasn't happy at all with the changes. Made you think you had a NIC or router problem the page loads got soooooooo slow. Nice that you can reset all the setting so much easier now, though.

ChaosLokkenDarien
ChaosLokkenDarien

nice tips. Not all of them should be used though. But some of them really are useful. Thanks! :D

ttsquare
ttsquare

I made the changes to the network.http.X.X stuff and it made dealing with Google maps a problem. Not sure why it would cause the problem, but at least know this is one instance where it might not serve you well. Regardless, I still like Wallen's stuff. Keep up the good work.

itssri
itssri

I tried the "speed up FireFox" (mine is version 3.5.2) about 10 days back and my browsing experience got screwed royally. I didn't think that this tweaking could be the problem and kept blasting my 384K DSL provider (because we had a thunderstorm around the same time). The poor guys checked everything over the last few days and finally suggested that I should try a format and re-install! Ha! Just now I had a brainwave and tried loading this very page which looked like it was on vacation. So, went in to about:config, filtered "network" and reset all the "userset" options to default and reloaded this page. And what do I see - the page came up in a flash. Valuable lesson learned...

MiaZoe
MiaZoe

I decided to ' Roll up my sleeves' ehemm, and do this yesterday - whilst doing so , I was expecting my Mac to blow up in my face :) however , I can modestly say that it took me all of 2 minutes to do this . When I restarted the browser I was amazed to see that it's running like a Marathon runner ! and all i did basically was just follow step 1 . :) thanks ?.

PeterPac
PeterPac

I have made some changes to the about:config and about:cache area of Firefox 3.5 and 3.1 versions which have changed the huge amount of memory being used. I tweaked it to where you close a tab or window and your RAM is actually recovered and Firefox acts in normal memory range. This does take minimizing Firefox after closing a tab or a window but on testing it reduced memory use from 100,000 plus back to 35,000+. I stated 35,000+ because it varied between 35,000 to 35,653 high. Firefox start up is kept around 35 to 36,000 instead of the reports I have read of up to 100,000 on start up. One other area is Microsoft has invaded Firefox by adding extensions or plug ins without the users consent. MS forced DRM and Net upon users. My question is, is MS now the internet police? Also, MSMedia Player hooks into Firefox even if u do not allow it. If you disable the above the next time u restart Firefox they will again be enabled. They also eat up RAM. I checked alert me if new posts so let me know if anyone wants my Firefox tweaks to low RAM use.

tomofumi
tomofumi

while it is good for the end-user, it puts extra stress to web servers, if there are many user access the server like this, it will just like a DDOS in sysadmins' point of view...

don.zeller
don.zeller

The tip to use "openintab" to open a new tab does not work.

ted
ted

Hack #10 is really unnecessary. Firefox has a built-in keyboard shortcut for going back or going forward. Simply use Alt-Left Arrow or Alt-Right Arrow.

keithc
keithc

I applied the first config hack to Firefox 3.5 and, while I didn't have any problems on my office network, at home only parts of pages would load and the browser would just spin, trying to load the rest, but never succeeding. Once I restored those prefs back to the defaults, everything works again. Anyone else have this experience with 3.5 (or any version)?

rderuiter
rderuiter

Note: this only works when all instances of FF are closed. But pretty handy: Search for 'retention' and find: browser.download.manager.retention. set the integer value to 1 (default is 2=keep; 0=don't keep anything).

colin
colin

Great list! Very helpful. Is there a way to disable 'Work Tools' toolbar from loading by default? I'd like Firefox to start without it and let me decide when to use it.

mcamire1
mcamire1

Number 1 slowed my browser to a crawl.

Tin Weasle
Tin Weasle

In my Firefox setup, I have no less than 8 files named "prefs.js" in different directories. Which one is the one to backup as a fail-safe?

jwildhair
jwildhair

browser.tabs.tabMaxWidth;100 makes all your tabs the same size so you don't have to move the cursor to close out multiple consecutive tabs/get to the 'X', provided you start from the left.

mike.sirianno
mike.sirianno

I would like to change the way Firefox displays bookmarks. Currently they are displayed descending. I would like them displayed similar to the way Maxthon 2 displays them. By columns and with the website icon shown. The about:config does have a setting for bookmarks, but I'm not sure what other value to enter. Thanks. mike.sirianno@gmail.com

techrepublic.posting
techrepublic.posting

Are you nuts? Disable Antivirus? You are just asking for trouble. If you worked for me and suggested this, I would fire you!

wpclarkiv
wpclarkiv

Great article; thanks so much for opening my eyes to "about:config". When I was exploring this file I noticed that I have +- 50 lines for the "Stumble-upon" add-on. I no longer have that add-on. How do I remove this info from the config file? Thanks so much.

rlharris4
rlharris4

The view source setting hasn't been honored since FF2.

tor
tor

The back button code in my Firefox now says 2; not 0 or 1. Back button works as "open previously opened page on this tab"; what does "up a page" mean compared to "go back one page"?

djohn86
djohn86

No. 8 is actually: extensions.getAddons.maxResults rather than: extension.getAddons.maxResults :D Awesome 'hacks' though..

rover3500
rover3500

Very handy,thanx.U 4got the 's' on extension in'extension.getAddons.maxResults'.Good job otherwise,is for people like myself that copy/paste

arjaym
arjaym

Thanks Jack! ---- Here are some useful hacks for Page Rendering; user_pref(?nglayout.initialpaint.delay?, 0); user_pref(?content.notify.ontimer?, true); user_pref(?content.interrupt.parsing?, true); user_pref(?content.notify.interval?, 100); user_pref(?content.notify.threshold?, 100000); user_pref(?content.notify.backoffcount?, 200); user_pref(?content.max.tokenizing.time?, 3000000); user_pref(?content.maxtextrun?, 8191); If you want lots of information about:cofig hacks, you can check it here. http://www.tweakfactor.com/articles/tweaks/firefoxtweak/4.html Regards!

trent_slabaugh
trent_slabaugh

Could you post the tweaks so the world can see :))

itssri
itssri

Yes, I had the problem and didn't realize that this tweak WAS the problem, because I also had an ISP outage around the same time and attributed the subsequent crawling browser to them poor guys.

dareeves
dareeves

As far as I'm concerned, ff3+ is the slowest browser in history. How did this happen? I think the way in which the security features have been added is forcing my to go back to v2!! This is plain pathetic, as they keep changing what used to work and forcing us to hack them all the time. NOT GOOD ENOUGH

ssaunders
ssaunders

Which prefs.js file do I backup? I assume the biggest one which is also the latest one. But I don't want to go into this without being sure.

computer.help.16105
computer.help.16105

Can you not use VIEW - TOOLBARS and UNCHECK the toolbar you don't want to view? Simply follow the same steps and CHECK the wanted toolbar to enable the same. HTH! C-bug

itssri
itssri

I reset all the speed up hacks and I am back to normal.

DVLnyc
DVLnyc

C:\Documents and Settings\user\Application Data\Mozilla\Firefox\Profiles\*********.default is the location shown in the video.

georgie_jungle
georgie_jungle

Use Ctrl-F4. It doesn't depend on the tab size to make closing easier and it doesn't have to start from the left side only but you do have to have the tab to be closed currently active. Closing a tab using ^F4 makes the next tab to the right active. If you close the very last tab on the right then the next tab to the left will be active.

elgeebar
elgeebar

You are a classic example of "a little knowledge is dangerous"! You'd fire the guy based on the headline... what a prat! If you had bothered to read what he actually wrote, the file's get scanned twice, once when downloaded by Firefox and once on the file system. Why waste time and resource doing it twice? Oh but of course that's what pointy headed bosses do!

interested_amateur
interested_amateur

Where you configure your browser the way you like it, not Microsoft. If you want a real treat, download this year's Mandriva distro (distribution or OS (operating system)). If you can click a mouse about 10 times, you, too, can be a geek using Mandriva. The people who coded Mandriva did so with people like you and me in mind. They tried to make the terminology Microsoft-centric for easier understanding. I only know Win ME and XP so it's been a learning curve, but a pleasant journey just the same. The open source concept is a little strange at first, but once you realize that the computer is yours... not Microsoft's, you'll find starting up your machine a pleasurable experience more and more. I use a folder of flower pictures as a pps. for my desktop background. The pics are set to change every 60 sec. If you're a mom or dad, you could use a folder of your kids' pics in a presentation. I have 'programmed' my mouse to Restore/Maximize a window by putting the pointer over the Titlebar and rolling the wheel one, single click to switch between the two sizes. What a help looking between a few windows displayed on your desktop... especially when copy/pasting. Anyway, my point is that this is a free, easily understood download and you'll kiss me in the morning for telling you. Go for it. Interested Amateur

georgie_jungle
georgie_jungle

The "View Selection Source" does not work with a replacement viewer but the "View Page Source" (Ctrl-U) on the menu does. Firefox v3.0.10.

interested_amateur
interested_amateur

I believe what is meant is 'up a page' means scrolling up one full page of your monitor height and 'back a page' means to return to the previous page you were reading. Clear as mud, right? LOL. Interested Amateur

georgie_jungle
georgie_jungle

2 for browser.backspace_action makes the backspace key do nothing for me...basically disabling it for page control. 0 is the same as using the Alt-LeftArrow key...view the web page you were on previously in the current tab. 1 is the same as using the PageUp key...it goes 1 browser window up on the page.

emtstephen
emtstephen

did you realizer these tweaks referenced at tweakfactor are from 2004. Just a note.

zclayton2
zclayton2

8 tweaks that give not a clue as to their effect. Yes, I want to buy a pig-in-a-poke. They may be wonderful, we just wonder.

itssri
itssri

I get the same experience in 3.* as in 2.* There is one thing I did and that is I have "clear cache on exit" on. I guess if you have a good broadband connection it's speedier to download content than have FireFox spend time to check the online content against the cache. The culprit may be the way FireFox stores cached pages. Well I don't know, I may be naive, but this works.

interested_amateur
interested_amateur

There are 2 Pref. files in Program Files > Mozilla > Firefox/... One is for security. Be careful!!! These files open in a Text Editor like MS. Notepad. Any changes you make are permanent. If you are unsure about making a change, write down what you are changing as a backup so you don't forget. Of course, the beauty of open source is if you screw up you can always re-load FF... LOL. Interested Amateur

Ocie3
Ocie3

Whether a downloaded file is scanned twice in succession depends upon the anti-malware software that is running and how it is configured. That is probably why Firefox is configured to scan downloads for malware just after the file is downloaded, which is a good feature since my computer runs Sunbelt Software VIPRE. VIPRE has "active protection" but as far as I can determine it doesn't automatically scan downloaded files. The user can select the file via Windows Explorer and choose to scan it with VIPRE via the context menu.

itssri
itssri

I tried the speed up FireFox options on version 3.5.2 and got doomed. Just now reset them and everything's back to normal.

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