>> Simple example: A M$ or Unix machine sends a file to the QDOS machine via
> TCP. It will send one or two packets, then stop and wait for ACK. Further > packets will only be sent after further ACKs. Your ACKs can only be > generated in 50 Hz rhythm, so packets will crawl one-by-one in 50 Hz > rhythm. (Or two-by-two, if you're lucky.)
AFAIK with TCP/IP this is negotiable. There is no need for such small window...
QLwIP offers a window of 8760, but I have found that neither Windows nor Linux will exploit that in their standard configuration, at least not as long as their counterpart has 20 ms latency. Depending on the application, they send one, maximum two packets before they wait for ACK.
Somehow QLwIP must live with standard behaviour of other machines, you can not expect people to tune their TCP stacks.
All the best Peter