We are in the process of upgrading from 8.8.1 to 8.10.4. As part of the migration we have also converted one of our large rule projects from Classic rule engine to Decision Service. We have deployed the decision service successfully. When we tried to deploy the service to the decision server, its taking double or more time than what it is taking in 8.8.1. We have followed the tuning guide for 8.9 version. But it did not see much of an improvement.

If your rule application contains lots of decision tables and if the decision table checking for Gaps and Overlaps is enabled, then the deployment performance will be significantly impacted. Around 60% of the time during the build seems to be spent running the gap & overlap checks. The time needed to deploy the ruleset for the first time can be significantly reduced by disabling the checks on decision tables (checks looking for Gaps & Overlaps) if you have lots of decision tables in the ruleset.