Try out
namebench. It hunts down the fastest DNS servers available for your computer to use. namebench runs a fair and thorough benchmark using your web browser history, tcpdump output, or standardized datasets in order to provide an individualized recommendation. namebench is completely free and does not modify your system in any way. This project began as a 20% project at Google.
namebench runs on Mac OS X, Windows, and UNIX, and is available with a graphical user interface as well as a command-line interface.
Step 1. Download NameBench
Step 2. Run NameBench
Step 3. Look at the top right of your HTML log, and in the box where it says "recommended configuration (fastest and nearest)" note the top 2 servers
Step 4. Use the first two DNS
Enjoy :) I gained 15% more speed :P