Best Practices for CABI scalability and performance. Troubleshooting is also addressed.
Release: 20.4 CU5 or higher
We highly recommend upgrading to UIM 20.4 and CU6 which is then fairly quick and easy so you can take advantage of the latest Jaspersoft (CABI) v8.0
What's New in Jaspersoft 8.x and Beyond
Highlight: Scalable query engine: New microservice application allows the system to offload Ad Hoc query execution from JasperReports Server to a separate service for better scalability.
TIBCO JasperReports® Server Performance Tips and Tricks
To understand how to troubleshoot any queries that appear to be slow, reference this KB Article.
UIM - Slow running Queries in CABI when creating an Ad Hoc report