Slow non-root logons, sudo and su commands

Hi, folks,

 In the last few weeks, our RHEL environment has begun to show very slow performance for logging in via ssh--about a ten second delay--for users authenticated via directory. There is no slowness logging in as root. This same slowness occurs when doing a sudo or an su command.

 I don't believe it's the directory--but what else would it be?

Thanks,

 John A