Logging in on version 1.37 of the Active Directory plugin takes too long and I think it is causing occasional proxy timeouts. At first I had blamed it on having too many groups in Active Directory. Then I took a look at the release notes and saw that version 1.37 add some extra group specific logic. I decided to try downgrading the plugin and sure enough I was able to log in almost immediately. Which made me very very happy!

Version 1.37 (I've seen this take up to a minute)

Apr 30, 2014 7:38:17 PM FINE hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider
Stage 2: looking up via memberOf
Apr 30, 2014 7:38:44 PM FINE hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider

Version 1.36

Apr 30, 2014 7:53:34 PM FINE hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider
Stage 2: looking up via memberOf
Apr 30, 2014 7:53:34 PM FINER hudson.plugins.active_directory.ActiveDirectoryUnixAuthenticationProvider