If you observe in ST03/ST03N that transaction SESSION_MANAGER accounts for large share in total response time.
There are following possibilities:
1. The load caused by the transaction SESSION_MANAGER, combined with the high roll in + wait time could indicate that the SAP Easy Access menu might not be configured correctly and should be tuned to improve overall response times.
2. Users have not been assigned with aproportionately large user menus.
How to check number of nodes assigned in Users Menu?
Start report "PROFGEN_CORR_REPORT_5" to analyze the size of the user menus.
If users have a user menu exceeding 2000 nodes, the corresponding lines will be highlighted.
Ensure there are reasonable number of nodes in the User Menu, refer below SAP Notes:
203617 - High memory consumption with Easy Access menu