You can also install Greasemonkey for scripts that unclutter and tailor a website to your needs. One Greasemonkey script I'll point out is the Neetzan Zimmerman Post Destroyer which, if you're familiar with Gawker, you'll totally understand.
There are a couple of tweaks to about:config you can make. First, set
falseto eliminate animated tabs. Second, change
falseto keep the download manager from opening when you begin a download. That progress bar uses a nontrivial amount of CPU.
You may be occasionally annoyed at how animated gifs slow things down, especially in forum threads where every user insists on having one for an avatar. The quickest way to nix them is by hitting the
esckey, but if you want to preemptively keep all animated gifs from looping, change
once(for animating through a single loop) or
none(for no animation).
One of my favorite tricks is something I got clued in on while using Classilla. Classilla masks itself as a mobile device so websites default to their mobile pages which load much faster. So just find a site's mobile address and a website that was glacially slow becomes an instant loader. This is especially true for Twitter. Compare www.twitter.com to mobile.twitter.com.
Finally, don't install too many add-ons if you don't need them as they can slow your startup time and take up memory. The only two add-ons I have are the above mentioned, and for ad blocking I have a UserContent.css file instead of Adblock Plus (the ad_blocking.css file embedded in Camino.app/Contents/Resources is a good starting point).