The simple way to speed up Safari
I recently investigated speeding up Safari and found some excellent pages but most appeared a little dated.
Here is what I did with Leopard:
1 - Quit from all browsers.
2 - Double click ~/Library/Preferences/com.apple.Safari.plist
3 - Open 'Root' and go to the bottom of the list to find WebKitInitialTimedLayoutDelay and WebKitResourceTimedLayoutDelay.
4 - Ensure that they are both set to 'number'.
5 - Double click the entries and set both numbers to 0.1
6 - Close the window and select 'Save' when asked to do so.
Perhaps those with more experience can improve on this.
Some historic background can be found here:
http://www.macosxhints.com/article.php?story=20050118152940322
Xserve and two 733 MHz G4s with Leopard !, Mac OS X (10.5.5)