What are recommendations / best practices to help prevent performance issues in Clarity in portlets/pages/lists? Some examples where this article can help:
Release: All Supported Releases
Component: Clarity Studio
This will improve initial load time.
End-users can create their own default filters using the manage filters option, instead of using “Show all” in filtering. If the portlet returns a large amount of data, setting a default filter that returns a smaller amount of results will help in optimizing performance.
Set AVP to a faster setting of: “Use only secured subpages to protect attribute values on this list” if not set already. Use this option instead of “Use display conditions and secured subpages to protect attribute values on this list” if you are not using display conditions. See AVP settings: Configure to improve performance for steps on how to configure this setting
Be sure the row is removed, and not just hidden, as the row will still calculate if it’s configured and not marked “Show”. Each row causes additional calculations which can slow down the portlet
The recommended amount of columns returned to be limited to 10-15.
See Performance Issues on Resource Planning Portlet Pages for additional known causes of slow performance on Resource Planning portlets
For slowness on an object on the Administration side, it's recommended to limit the amount of attributes to 100 where possible. As referenced in the Clarity PPM Studio Objects and Attributes documentation, a high number of attributes can result in performance issues and the potential failure of subsequent upgrades. Consider creating a subobject rather than assigning many custom attributes to a single object.
Compare if the portlet NSQL is the same as an environment that is not having the issue.
Obtain the trace and run the parameterized query directly on the database to review the performance.