I need a solution
I've noticed this problem after upgrading my user base to SEP 12.1 RU2. It appears that DefWatch scans take anywhere between 30 minutes to 1 hour to complete. This is a quick scan that should only take 2-10 minutes at most, considering it only touches 1,000-2,000 files roughly. I've also attached the vpdebug log as well.
Screenshot of the scan log.