Performance tuning a WCF with netTcpBinding

We have a WCF service consumed by an ASP.NET application which is not where we would like it to be with the speed开发者_JS百科. The slowness is seen at the networking level, not in the processing. So for example it takes 100 milliseconds for the processing, however it takes 600ms for transporting 27,000 bytes of data from one machine to the other (confirmed via wireshark).

We have disabled secure connection. The test is being run on a machine with no load, and the two machines are on the same LAN.