We don't recommend changing the Response and Acknowledge timers, unless you really know what you are doing. You can experiment with the Inactivity Timer, if you often get timeouts from the hosts. While selecting the MacDFT Config CDEV, pressing Command-T brings up the Group 1 Timers window with three timers. Only experiment with the Inactivity Timer, which is the bottom value. We don't expect changing these values would increase the performance of MacDFT.
The performance differences between the machines is not due to the block or even packet size (if both systems are on Token Ring), but is most likely due to MacDFT's intrinsic program speed. However, if the PS/2 is a LU and is "directly" connected to the controller, and, if the Macintosh is a PU having to go through a gateway, there can be substantial performance differences. Or if the PS/2 is on Token Ring, and the Macintosh is on coax, the PS/2 will be faster. But again, if everything else is equal, the Macintosh will still be slower.
In file transfer for example, under TSO when you transfer a file you allocate space in blocks, tracks, or cylinders by specifying BLKS, TRKS, or CYLS. Under CMS this is done automatically, depending on the file type you select, and can't be changed by the client. And even under TSO when you allocate the space, this doesn't influence perceptibly the throughput performance.
Data is sent one buffer-full at a time, and the buffer size is set to be the screen size. So, if your terminal is configured to have a 80*24 screen, during file transfer approximately 1920 bytes will be transferred at a time.