Is your DNS server slow - the key to your answer is Nambench

If you are frustrated with your ISP's DNS, Namebench  will find the fastest DNS for you.  This ended my frustration changing through trial and error.  My ISP turned out to have the fastest DNS - Namebench found servers that were much faster the the default.  Google and Open DNS were much slower.  Namebench is available for many platforms including OS X and Windows.