Hi Mario,
As Amlan mentioned about FQEVENTS, please check coding of all the enhancement done. First you need to identify which one is taking longer time its dunning proposal or dunning activity. Follow below steps
1. Execute dunning proposal and dunning activity separately to analyse which one is taking longer time.
2. Take help of technical person to find all the enhancements implemented related to dunning.
3. explain process and get code review done some technical person.
At last deleting entries from standard table is not solution of performance issue. So please dont do it.
Regards,
Gulrez