One of the few complaints I had about the refurb MacBook I purchased last month was Safari hanging for 5-10 seconds on certain sites. I mentioned this to a friend, and he gave me a link to Google Public DNS. I made the recommended changes to the DNS numbers, and now the problem is totally gone. The instructions refer to Leopard, but it worked for me on Snow Leopard 10.6.4, and Safari 5.0.1 now opens everything fast as hell.
http://code.google.com/speed/public-dns/docs/using.htmlExample: Changing DNS server settings on Mac OS 10.5
1. From the Apple menu, click System Preferences, then click Network.
2. If the lock icon in the lower left-hand corner of the window is locked, click the icon to make changes, and when prompted to authenticate, enter your password.
3. Select the connection for which you want to configure Google Public DNS. For example:
◦ To change the settings for an Ethernet connection, select Built-In Ethernet, and click Advanced.
◦ To change the settings for a wireless connection, select Airport, and click Advanced.
4. Select the DNS tab.
5. Click + to replace any listed addresses with, or add, the Google IP addresses at the top of the list: 8.8.8.8 and 8.8.4.4.
6. Click Apply and OK.
7. Test that your setup is working correctly; see Testing your new settings below.
8. Repeat the procedure for additional network connections you want to change.