Note that some people have found that setting DefaultRcvWindow in the [MSTCP] section of the SYSTEM.INI file under Windows for Workgroups to 3072 gives a big improvement.

My own experience with DefaultRcvWindow is that I get a much better performance with a large value (16384 or larger). Other people have reported that anything over 3072 slows things down enormously. One person even reported a speed drop of a factor of 30 when he went from 3072 to 8192.