Some new users running very slowly in local lab setting

All, forgive me if this question is too trivial, but I have been forced as an untrained professional into a sysadmin role for a local-network classroom lab on my campus, and my IT department claims no knowledge of anything Linux related.

I recently had a multiple drive failure in my RAID, necessitating a reinstallation of RHEL on my server. I had to recreate the user accounts, and have discovered that some of the new accounts appear to be running very slowly, while others seem to run fine. The output of top doesn't indicate that there are any runaway processes slowing things down.

My configuration has always been to use NIS to distribute user accounts in the 10 seat lab, and NFS to share the /home directory among the client computers. I believe that these systems are running properly, based on checking rpcinfo and service nfs status on client and server. Plus, df shows the mount is working, and I've not seen any NFS errors. NIS seems to be working, else I wouldn't be able to login. But, in the affected accounts, it takes 30 seconds to open a terminal window, and roughly the same amount of time to switch between windows. In others, everything seems to run normally. I created all of these accounts at the same time, and new accounts created this morning to test the setup all have this slow-running issue.

Can anyone please suggest where else I should look for errors? Could it be a network hardware issue to affect different users differently? Time is, as usual, of the essence as I am expecting a class to try to use this lab later today, and I have to fit my work in the lab in around my own course load.

Thanks for any advice you could provide,
Todd
SUNY Oneonta