ftp very very slow

Others and I have had problems with very very slow ftp on Neutrino
ftping to Windows 98 machines and OS/2 machines. We are running an
ethernet card on a 10/100 switch hooked into the site lan. If I run
Linux or something else on the same hardware, there is no slowdown.
Does anyone have any suggestions for what to try and what might be
wrong? nicinfo shows no transmission errors. Thanks.