in the test realm patch notes it reads
"Reduced network latency by disabling the Nagle algorithm."

I recently came across a post which shows how to disable nagle algorithm system wide (usually you do it per TCP socket).
http://forums.worldofwarcraft.com/th...sid=1&pageNo=4

it reduced my ping by about 100-150 ms

this is quite lol but its Blizzard so what can you expect?? 9.3 million people play WoW, and one patch and several years down the track and they discover this!!