Socket Read / Write Buffer

[j7n 0]

In Settings -> Advanced -> Experts Only, there are 2 options for setting the socket buffers. They are by default set to 64k. Believing they control the TCP window, I've experimented with them, increasing them and also setting them to 1500-1460-1000 (expecting poor speed), and restarting the program. But the changes had no definite effect. I was still able to download around 1 MB/s from known "fast" hosts.

My system is Windows XP. Increasing the global receive window from the default ~60k about four times did affect download speed by the same ratio, while no such effect was observed when tweaking the socket buffer in Apex.

What exactly do these options do? Is the 64k or some other value hardcoded and cannot be changed?