<Batch_rule_group> running very long in ItemPlanning RPASv15.0.1.8

Hello Experts,

Our Batch_rule_group Job is deteriorating in its performance week by week. At the start it was running for 4-5 Hours now its close to 10 Hrs. I would like to request if there's any way in Finding out un-used rules and splitting  rules into parallel groups. Help on this would be appreciated.Thanks!

Running Expression/Utility as part of Job:

mace -d <GLOBAL_DOMAIN>  -run -group $RULE_GROUP -loglevel all -processes max

We have around 2.5 million CC's (Customer choice) in our system. Among which 700K are valid and remaining needs to be purged from Domain and RDM. We are stuck with Purge process for which an Oracle SR is already in place.Thanks!