I read in TechCrunch that Google open sourced its web page optimisation tool called Page Speed which they use on their websites. I thought you may want to check it out. It is a companion to firebug. Also found an extention from Drupal.
I ran it on Gridrepublic.org jsut to test it out and there were a few very easy suggestions for GridRepublic such as compressing a few images and making them browser cashable. This could reduce bandwidth use and increase performance in general.
Here's the link: http://code.google.com/speed/page-speed/
Knowing you're looking at Drupal. There is also a drupal optimiser extention for firebug (from the drupal team) as well which you may want to check out. Link: https://addons.mozilla.org/en-US/firefox/addon/8370 The Drupal for Firebug module has to be installed/enabled for this to be used.
