Obviously I meant to ask if performance is affected during VACUUM.
@pg-gadfly's link answered it for me:
> VACUUM creates a substantial amount of I/O traffic, which can cause poor performance for other active sessions.
@pg-gadfly's link answered it for me:
> VACUUM creates a substantial amount of I/O traffic, which can cause poor performance for other active sessions.
A common misconception about (auto) vacuum is, that you need to turn it off, to avoid performance problems.
The truth is: you need to make it more aggressive (= run it more frequently) if you have problems with the (additional) I/O load it generates.