Huge load after update from 2.3.16 to 2.4.12

[plate at bibliothek.uni-kassel.de]

Hi,

[...]
>
> How many mailboxes on the system? Took us about 2 hours to come down
> from loads over 500 after the upgrade with 10,000 active user accounts.

just around 200 ;-) but its our Backup MX an mailman is running too, so a
mail to every user produces that load. The machine is a bit...old, just 2
GB of memory and a RAID5.

CU

Michael