I know that there have been a number of hints about Safari slowdowns under various updates of OS X. I got hit this time, after applying the 10.4.2 update. When clicking on a link, there would be a *long* pause before anything would happen. I shut off the firewall, quit all my other apps, restarted, etc., but all to no avail. I already have entered my DNS server numbers in my Network location setting, so I knew that wasn't the problem.
The solution in my case, was deleting ~/Library/Safari/history.plist. I did so, and then my Safari was back to loading pages faster than my 2.4 GHz P4 PC (IE or Firefox), thank you very much.
Here's how I tracked it down. In the Terminal, I ran this command:
$ sudo fs_usage -f filesys
I noted a number of hits to the history file, and decided to delete it. You could, of course, use sudo fs_usage for a broader monitoring of what is going on behind the scenes. From man fs_usage: "fs_usage -- report system calls and page faults related to filesystem activity in real-time."
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050720113322218