You can set a threshold in the SmartView Monitor to send an alert (SNMP, Mail, User Defined) when CPU or memory utilization exceeds a certain amount. This topic was covered in the third edition of my book. The destination for the alert is set in the SmartConsole under Global Properties...Log & Alert...Alert Commands. Note that setting alerts for policy installation events as mentioned in the book can now be configured directly in the SmartConsole by using SmartTasks in version R80.40+.
Gateway Performance Optimization R81.20 Course
now available at maxpowerfirewalls.com