How Stardeveloper.com achieved 120% improvement in website load time?

Stardeveloper.com got an improvement in average load time of a web page from 8.6 secs to 3.9 secs. This improvement was attained using static resource caching using Expires and Cache-Control: max-age HTTP headers. Author shows charts from Google webmaster tools to show what the average load time was an year back and what it is now. Then he moves on to explain what this technique is and how you can implement it on your own ASP.NET website in just a couple of minutes.