high memory usage after 0:00u

[joximu]

cron:
I'd put the backups to some later ("0 1 * * *" instead of "@daily" - or something similar)

worker/prefork:
worker is better in performance (with threaded processes or something like this :-) - but mod-php cannot deal with that, so with worker you need fastcgi, prefork can deal with both fastcgi and mod-php - but since fastcgi is more secure but less performant you have to decide...

/J