The Windows NT socket driver, Afd.sys has a 8KB default receive buffer. If it fills, processing halts until the entire buffer is transfered to the receiving program. This may result in a time-out.
RPC programs, that use Winsock over TCP/IP, can benefit from an increased buffer size.
You only need make the change on computers that are receiving more than 8KB of data.
Use Regedt32 to navigate to:
On the Edit menu, Add Value name DefaultReceiveWindow, as a type REG_DWORD. Using the decimal Radix, set the data value to the number than yields the best performance. You can try 16384 for starters.
Shutdown and restart the computer.