Performance issues can be seen if a large number of dynamic substitution variables are created but not cleaned.
Performance issues can manifest as:
Release : 9.3.x, 9.4.x
Jobs, Components, and/or Process Flows are configured to create Dynamic Subvars but those Dynamic Subvars are not cleaned after it is used.
This causes a build up of the number of Dynamic Subvars in the SO_SUB_VARS table resulting in a performance decrease in the time it takes to perform procedures and functions related to the SO_SUB_VARS table.
The number of rows in the SO_SUB_VARS table before a performance issue may be seen may differ from environment to environment but can be as little as 5,000 rows.
Delete all dynamically created subvars that is no longer needed.
It is best practice that dynamically created subvars should be deleted within the same Job or Process Flow in which it was created.