Google Reader (1000+)

"The current crop of Prospector Experiments includes Speak Words for location bar search completion; Instant Preview for faster page loading from location bar suggestions; Find Suggest for search suggestions when using the in-page Find tool; and Start Faster makes a customization tweak to how Firefox starts when you've just turned on the computer. The short version is that it does what it says it does: Firefox will start faster when you've got it running, at least after you immediately restart your Windows box.

The slightly more technical explanation is that it bypasses the Windows prefetch feature. The add-on will install a Faster Firefox icon on your desktop, which has to be used to start the browser after a Windows reboot. To double-check that it's working properly, the developer recommends using the About:Startup add-on, which is also restartless.

Type 'about:startup' into your location bar and you'll get, in milliseconds, how long Firefox's main process takes to start; how long it takes for XRE_main to be called, one of Firefox's first called functions; how long it takes the tabs from the previous session to be restored but not reloaded; and how long the firstPaint takes, which is time it takes for the the first tab you're looking at to fully load."

Source : Google Reader