I thought that the ```EnginePerformanceMonitor``` is to be used in a different way (when inserted in a loop or in a celery task), by passing a not-unique string as first argument, such that you can group stuff together. E.g.
```
with EnginePerformanceMonitor('saving output', job_id, ses_and_gmfs):
    ....
```

Maybe we need an additional "description" field in the Performance table?