Our Windows domain is in a forest of about 35 other domains.  When starting 
winbind on a member server it attempts to contact the domain controllers for 
every single one of the domains in the forest.  The server doesn't have 
privileges to access any of the other domains, it can't authenticate.  It 
takes about three or four minutes for winbind to try connecting to all of them 
and during that time is completely unresponsive to queries.  While it is 
unresponsive wbinfo and smbd both block on winbind lookups and are useless.  
After about four minutes it starts working and answering queries but with the 
winbind cache interval of 300 seconds, the unresponsiveness kicks in again as 
it retries them all.  That gives about one minute of usability every five 
minutes. 

This may be related to bug #704 and at least one query I saw on the Samba 
mailing list.  I can attach a winbind logfile if that would help.