Troubleshooting “slow” reports in PowerBI Report Server (or SQL Server Reporting Services) can be an arduous task. End users are often unable to provide detailed (or reliable) data that a report took longer to load today than it did the last time it was run. Even if a user states that the report is now taking 10 seconds longer to load, that additional time needs to be attributed to a specific step in the report generation process before it can be improved/fixed.
In the report server database (ReportServer by default) there is a view (ExecutionLog) that can provide detailed statistics about each execution of a report. Note: ExecutionLog3 view is the newest/current version and the ExecutionLog and ExecutionLog2 views are for backwards compatibility. By default the execution log entries are retained for 60 days.
The view that Jamie shows also works for SQL Server Reporting Services reports, so it can help there as well.