I'm running PG 7.4.1 on FreeBSD 5.2.1_RC1 and experienced a general
40% drop in performance after increasing Shared mem buffers to 2000
(from the 1000 default setting) and the Sort Mem to 1024 from 16.
After changing the .conf file back to the original values, performance
didn't change back. Only after dropping the database and reloading
from dump, did performance return. Is this unusual behavior in
anyone's opinion? (Note that I didn't forget to do a pg_ctl reload to
have postmaster re-read the .conf file.)