You can view the performance of the iOS device used for testing your app. This feature will be useful if you wish to keep a track of the performance of a device while testing an application.
To view the device performance, just click on the 'Logs &Performance Metrics' icon as shown in the image below.Click on 'Performance', you will be able to view the device performance.
Device performance like Memory Usage and CPU Usage will be displayed on graphs.
You can also view the performance details once your testing session is complete.
Just navigate to 'Reports', select the device and click on Performance Graphs.