slow peformance with auth and it's weird

[Jeremy Hansen <jeremy@methanesea.com>]

I'm using ldap for auth on a few machines.  Here's the scenario and i 
don't quite understand it.

login ssh as root

su - joeuser

then

joeuser$ su - joeuser

as joeuser

and at this point it takes a large amount of time to get the auth.  The 
auth succeeds but just take a large amount of time.

Now, if I login as joeuser initially and su - joeuser, it works in a 
flash.  So why would the extra su from root add some delay.

Also, any pointers to performance tuning suggestions for openldap?

Thanks
-jeremy