I have JIRA v5.2.8 (running on Ubuntu 12.04 x64) configured to use our OpenLDAP server for user authentication (not group membership however). Currently we have an Apache2 server as a reverse proxy configured in front of JIRA with basic authentication enabled.
Today, I noticed that the Apache/JIRA combination is doing a search/bind on our LDAP server multiple times per request on every request. This is hampering performance and shouldn't be neccessary.
I know that tools like Apache2 have an LDAP cache to improve performance and I have verified via two different methods that this cache is functioning normally. The http://localhost/ldap-status on the reverse proxy reports the cache is working and other servers (Confluence, Nexus, Jenkins, Fisheye, etc.) do not have this problem of over-taxing our LDAP server.
I also ran a test on JIRA where I logged in directly without going through the reverse proxy and JIRA does seem to cache credentials because after the initial lookup, additional lookups where infrequent.
So the problem must be the combination of basic authentication and JIRA that causes this issue. Again, neither Confluence nor Fisheye exhibit this problem.