Fabio,
> We run VACUUM ANALYZE after we remove about 1000 rows every hour on the
> halh hour. Our max_fsm_pages is set to 10000
Have you checked how long these vacuums take? If they are starting to
overlap, that would explain your high CPU usage and poor performance. You
might want to consider raising FSM_pages and vacuuming less frequently.
--
-Josh Berkus
Aglio Database Solutions
San Francisco