Chris Webb uses Diagnostics.Trace to track process runtime in Power BI:
To sum up, the workflow for tuning your query is:
Make some changes to the LongQuery query that hopefully make it faster
Update the Trace Message parameter with some notes about which version of the LongQuery query it is that you’ll be testing
Click the Refresh Preview button for the Diagnostics query to test how long LongQuery now runs for
Refresh, or load, the query that reads the data from the trace logs so you can see how all of your changes have affected query execution times
I give it two months before the Power BI team releases a change to make this easier…