Although we all love to use Firefox, we have to admit it’s not the fastest app to launch. I always thought that its bottleneck was its modular XUL plug-in technology. After all, extracting plug-ins from compressed containers, then interpreting and integrating the contents to the app each time it launches, on-the-fly does take some CPU time, disk ops and memory allocation time.

Firefox 3 however has some improvements that should make it a phenomenal foe to IE7 when it comes to speed.

• Defragmentation, which has reduced memory usage after startup in more than one third.
• Image cache, fonts cache, back/forward cache, and more. They have all been tuned up to free used resources after certain time of inactivity.
• Uncompressed images are discarded from memory after a while if not active.
• More efficient animated GIFs storage in memory.
• About 400 memory leaks have been hunted and taken down thanks in part to better tools to identify them.
• A cycle collector takes care of objects referencing each other preventing either of them being cleared from memory.