I was invited to write a more comprehensive post about it for Speed Awareness Month. The purpose of this month (August incidentally) is to make web developers more aware of performance related topics. Digging into their archives is a good way to get started. And in case want to see how CDNperf came about, you probably want to read my guest post.
In other news I will be taking this month off. As a consequence I will be writing a lot less than usually. Time to recharge batteries and all that.