You can monitor thresholds from the Manager Dashboard pages.
Click the numbers listed against the device to be monitored under the warnings column of the System Faults monitor.
System Faults monitor.png)
The Faults tab in the Logs page displays the list of warnings for the selected device.
The warnings relating to the Sensor performance monitoring thresholds are listed as a Device Performance - Memory Usage - System Memory fault type.
Warning dialog.png)