pingfreq is the number of seconds between PINGs from the server (something between 90 and 180 is recommended).
Possibly a dumb question but...
Would increasing or decreasing this number have any affect on the number of users timing out? We seem to have a quite a few users timing out lately. Rpings between servers seem fine.
If it is already high (like over 150), you might want to try something lower. If it's under that, try something higher. When you change the pingfreq, be sure to wait and observe the new timeout rate for 24-48 hours before changing it again.
Technical info about IRC pings:
IRC servers use the PING/PONG command to keep the connection active, and to make sure the client on the other end didn't lose the connection. If a client does not send back a PONG from 2 consecutive PINGs it is considered to have not received the PING, and the connection is terminated by the server.