You might be surprised by the add-ons and extensions that have wormed their way into your copy of Firefox. You can work your way through the list of add-ons in your browser, disabling and uninstalling those you don't need. Or you can save time by opening Firefox with all add-ons and extensions disabled.
To disable all of Firefox's add-ons, you have to open the browser in its Safe Mode (no relation to Windows' own Safe Mode)
Click Start >All Programs >Mozilla Firefox >Mozilla Firefox (Safe Mode)
A quicker way is to press the Windows key (in XP, follow this by pressing R), type Firefox -safe-mode, and press Enter.
Disable all add-ons in Firefox by starting the browser in Safe Mode and selecting the "Disable" option. (Credit: Mozilla)
In the Firefox Safe Mode dialog box that appears before Firefox opens, click "Disable all add-ons" and choose the Make Changes and Restart button to run the browser with no add-ons or extensions enabled. We can't tell you for sure that every feature of every Web site you visit will work as designed, nor can we say unequivocally that you'll be browsing faster with no add-ons enabled. But we have made the rounds of my favorite sites in each browser's no-add-ons mode and didn't feel like we were missing anything.
Disabling add-ons and extensions one at a time is a snap in Firefox.
Click Tools > Add-ons, select an entry under the Extensions tab, and click Disable.
To toss an extension, click Uninstall. You can disable (but not uninstall) Firefox's plug-ins by clicking the Plug-ins tab, selecting an entry, and clicking Disable.
You'll find more information about Firefox add-ons at the Firefox Support Knowledge Base.