The never-failing macosxhints.com is at it again, this time with a series of tips concerning Safari, speed and bookmark management. This tip
offers a simple method for using the Finder to sort Safari's bookmarks alphabetically (hint: make sure you hit cmd + j in the Finder and enable the 'Keep arranged by name' option), while this tip
points out that Safari can receive a noticeable speed boost if you organize as many of your bookmarks into folders as possible.
If you're really looking to speed up Safari, the speed boost/folder tip
also contains a roundup from Rob Griffith of quite a few other macosxhints tips that can re-energize Safari's experience.