Are you doing this on the site listed in your profile? From what I can see with a 27ms RTT request, there is a 9ms pause after the GET ACK and content -- and then only 4 full packets before an RTT. That's close to the limit of my initial window (5880) before content ACKs arrive. That would seem like a typical result unless/until clients start tuning their initial window as well... which was kind of the point of Google going public on this. Have you seen much aggregate benefit beyond a window increase from 2 to 4?