Hi Molly,
In the HANA studio open the admin prospective and go to the performance tab. This tab provides a lot of details about the current HANA load. While you procedure is running you should check 'Blocked Transactions' and 'Expensive Statement Trace'. Those areas might offer a hint.
You could start the HANA admin console, HDB admin, and take a performance trace restricted to the user running the procedure.
You could attach the debuger, from HANA studio, to the session that calls you procedure and step through it.
I know the statistics servers uses _SYS_ STATISTICS for reporting, but I don't know which table or view has information about procedures.
Best regards,
Duncan