I had >30k users on a bunch of systems in 2001 (I inherited that approach, mind, I'm not -recommending- it). We moved to LDAP a couple years later because it w

I had >30k users on a bunch of systems in 2001 (I inherited that approach, mind, I'm not -recommending- it). We moved to LDAP a couple years later because it was a much nicer architecture to deal with overall, but performance and consistency weren't problems in practice.