[ajb]

Buffer size is the product of bandwidth and delay, so if communicating with something close, it can still go fast.

Had an illustration of this once when my then-employers IT dept set up the desktop IP phones to update from a TFTP server on the other continental land mass. Since TFTP only allows one outstanding packet, everyone outside head office had to wait a long time for their phone to update, while head office didn't see any issue.