Hi Quanah, yes, it takes 5–7 seconds for each search.
I believe that's a general known issue with very large groups. I personally moved to using dynamic groups via slapo-dynlist for a variety of reasons, performance being one. You may want to test in a dev environment if your issues go away if you move to dynamic groups instead.
--Quanah -- Quanah Gibson-Mount Product Engineer Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: <http://www.symas.com>