Why is db slow after analyze?

[Greg Moore]

I ran dbms_stats.gather_database_stats( ); on a test machine with no other users.  After this, running a simple query on dba_extents was extremely slow.   Does anyone have an idea on what's the likely cause of this?  I'd like to check after gathering stats, but am not sure what to look at to verify why the simple query runs so, so slowly.  (Bouncing the db brings things back to normal, but doesn't help me understand what the holdup was.)   Thanks.