i had come across a video at TechRepublic.com entitled "IT Dojo: Firefox about:config hacks that can speed up and customize your browser". Along with it is a transcript of the video which i had summarized as follows. Hope you firefox peeps will benefit with this hacks.
Unbeknownst to many users, Firefox has a whole host of application settings (called preferences) that aren't found under the regular Options or Preferences interface. These preferences, both hidden and not, are stored in a prefs.js file. Prefs.js is a plain text file located in the Firefox profile folder. You could edit the file using a text editor, but there's an easier and somewhat safer way. You can access and modify Firefox's hidden preferences by using its about:config feature.
Just remember that about:config and many of the preferences it can access are hidden for a reason. About:config is a much more powerful configuration tool than Firefox's standard dialog boxes. This means that it's also much easier to really mess things up if you make a mistake. In fact, when you launch the about:config page for the first time, you must accept an agreement warning you of tool's dangers before you can proceed.
So to be on the safe side, It is highly recommended that you back up your prefs.js file before you start editing. Then, if something goes wrong, you can restore your original preferences by copying the backup over the corrupt file.
If you're unable to restore your preferences that way, 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. This will probably get you back up and running, but remember it will restore all user preferences to their default values.
Now with all the warnings and recovery instructions out of the way, let's open about:config tool.
Launch Firefox, go the Address bar, and enter about:config. Once the page is open, you'll see a very long list of preferences (one per line). Each entry has a searchable keyword. The entries can be a Boolean, integer, or string value and each entry contains a Name, Status, Type, and Value. Typically, you will be modifying only the Value, by double-clicking on it and making the change.
Now that you're in and know how to use the tool, let's look at a three handy hacks.
First, if you have a broadband connection and want to speed up Firefox, you can tweak the browser's HTTP pipelining and max connections preferences.
Enabling pipelining allows Firefox to make multiple requests from a responding server without waiting on a response, and tweaking max connections will increase the number of simultaneous connections Firefox can have with a single or multiple servers.
To find the about:config entries we need for the first part of this hack, search for pipelining in the filter. Within the results, there are three entries that we're interested in.
Locate network.http.pipelining and change this to true. Then find network.http.proxy.pipelining and also change this to true. Lastly, find network.http.pipelining.maxrequests and change this to value to 8.
Now enter max-connections in the filter. Find the entry network.http.max-connections and change this value to 96. Locate network.http.max-connections-per-server and change it to 32.
If you're like me and you hate the annoying countdown that occurs every time you install a Firefox extension, there's an about:config preference that can disable it.
Search for enable_delay and you should see the entry security.dialog_enable_delay. Change this value to 0.
Lastly, here's a tip for all of us who didn't win those elementary spelling bees. By default, Firefox checks spelling only in multiple-line text boxes. You can set it to check spelling in all text boxes. Enter spellcheckdefault (all one word) in the filter and you should locate the layout.spellcheckDefault entry. Change this to 2.
