In the past we offered settings to disable the nagle algorithm and adjust the send buffer, adjusting the recv buffer isn't nessary as by default it's quite large.
Most people adjusted these options without realizing the effect and then complained when the performance suffered. I don't recall anyone benifiting from these options. The options were removed.
There is one other option you can try which is to enable high thread priority.
http://forum.flashfxp.com/showthread...&threadid=1218