Andrew Hill <andru@treshna.com> writes:
> If I dump the databases and recreate them from the dumps the load
> average on the server returns back to normal for a week or two before it
> starts to get really slow again.
I think you are suffering from either table bloat or index bloat.
To figure out which, watch the pg_class.relpages values for your
heavily-updated tables and their indexes. (Note these values are
updated only by VACUUM, so try recording them right after each routine
VACUUM.) Once you know what's growing, we can give some advice
about what to do.
regards, tom lane