Silly Window Syndrome
[See Stevens, volume 1]
Commonly exhibited by NT4 TCP client stack when sending bulk data.
From a mailing list: "The work-around was to change the tcp_deferred_ack_interval parameter in Solaris 8; this parameter indicates the delay in milliseconds before sending a deferred ACK (the default for windows is 200ms, for Solaris 8 is 100 ms and for most linux distributions 50ms; I set it to 10ms and the file uploads are 10 times faster!).
I believe the new low value of 10ms is OK for LANs (where RTT for TCP packets are less than 10ms) but it may not work for WANs."
File uploads to AOLserver, tclhttpd, ... can exhibit this.