Erland Sommarskog (8/16/2013)
... but it may be the fact that the jobs adds a lot of rows to some tables and so on.
Maybe this could be a reason. Once per week, job deletes all data from 16 big tables and writes them again.
Biggest table has about 76 millions of rows. So, I guess deleting and re-creating 76M of rows could be harmful for all queries which use that table?