I came across Google’s Namebench program while researching internet connection slowness and found that I could increase my DNS lookup time by 191%.  This may not work as well for you but it’s worth a try.  I am on a city fiber network (Spanish Fork City Network) that I’m pretty sure is getting too big for it’s servers.  When I typed in www.google.com for example, it would take up to 5 seconds sometimes for the web page to resolve.  After using the recommended DNS IP adresses from namebench the resolve time is under a second.  It recommended using Comcast’s DNS servers.  Learn more at http://code.google.com/p/namebench/