Firefox’s address bar, also known as the Awesome Bar, stores all sorts of awesome information in a SQLite database. The SQLite database slowly starts getting fragments and the Awesome Bar just isn’t as awesome if it gets all laggy. To solve this, you can vacuum the SQLite database that Awesome Bar used.
Go to Tools, then Error Console. And copy the following:
Components.classes[ "@mozilla.org/browser/nav-history-service;1" ].getService( Components.interfaces.nsPIPlacesDatabase ).DBConnection.executeSimpleSQL( "VACUUM" );
And paste and click on Evaluate:
Vaccuming Firefox in Error Console
The browser probably freezes for a few seconds and the address bar feels faster.
[via MozillaLinks]