Tony Gentilcore Mozdev recently released Fasterfox, performance and network tweaks for Firefox. Features include:
Prefetching - Fasterfox uses idle bandwidth times to pre-fetch and cache the links on your current page.
Network Tweaks - You set how Fasterfox controls simultaneous connections, pipelining, caching and more.
Pop-up Blocker - It blocks Flash plug-in pop-ups now.
Page Load Timer - Shown here, this tests the effectiveness of your settings. After all, it's called Fasterfox, not Moderatelyslowfox.
Thanks to Subramanian Muralidharan and Brian Hysell.
Fasterfox [Mozdev.org]