As part of that article (
How to Optimize the 'Big Four' Mac Web Browsers) is a nice little DNS server benchmarking/rating reference:
namebench.
I ran it after having a while back switched to Open DNS servers (which were better/faster than those supplied by my ISP) and found that Google Public DNS had the fastest response; it was twice as fast as Open DNS (and there are claims that it is more secure from malicious tampering).
