Why CA TDM Portal has become slower and slower progressively to the extend that simple task like fetching a table level detail and then updating a 'tag' in modelling takes several minutes. 

The following could cause the slowness:

. Available TDM Portal memory is used.

. Indexes on repository database not created.

. Repository maintenance can be done to improve performance.

Release : 4.8.148.0

Component : CA Test Data Manager

The new version TDMWeb-4.8.165.0.zip should resolve the issue Or as an alternative create table index in the Repository database manually with the below query.

CREATE INDEX gtrep_dd_ent_attrd_entity ON gtrep_datadisc_ent_attr_def(entity_id);

How to Perform Repository Maintenance in Test Data Manager- Datamaker: https://ca-broadcom.wolkenservicedesk.com/external/article?articleId=9607

Increasing CA TDM Portal JVM memory: https://ca-broadcom.wolkenservicedesk.com/external/article?articleId=10602