According to this software:
http://www.grc.com/dns/benchmark.htm, my ISP's DNS is the fastest. It isn't the most secure of course.
What did surprise me is that DNS Advantage and Comodo Secure DNS were very similar in speed and near the top, but OpenDNS is the fifth slowest.
Guess I'll be switching, since I don't use OpenDNS for anything other than blocking malware sites.