Telnet problems with 3c509

[Maatman Arnold]

Ha reader, please don't get angry if I place my question in the wrong list
or if I use this list in a wrong way.
I have problems with a 3c509 in a classroom where I want my students to
telnet to a Linux (redhat 5.2) machine (pII, 64 MB ,2 Gb). It takes a long
time to get a connection (before the login prompt appears), after that some
commands  (like ls) give a quick response, other commands (like who) are
very slow.
Maybe someone can help me with this problem.
Thanks for your responce,
regards
Arnold Maatman
Rijn IJssel College
Arnhem
Netherlands