hi michael
>> Have you ANALYZEd your database? VACUUMing?
>
> Of course ... before 8.1 we routinely did a vacuum full analyze each
> night. As of 8.1 we use autovacuum.
what i noticed is autovacuum not working properly as it should. i had 8.1
running with autovacuum for just 2 days or so and got warnings in pgadmin
that my tables would need an vacuum. i've posted this behaviour some weeks
ago to the novice list requesting more infos on how to "tweak" autovacuum
properly - unfortunately without any respones. thats when i switched the
nightly analyze job back on - everything runs smooth since then.
maybe it helps in your case as well?
cheers,
thomas