Why is my System event log full of WMI Performance Adapter messages?

Are you using System Center (or some other remote management console that uses WMI) to monitor\manage this system? That's what generally triggers those events in my experience. These are just events, not warnings\errors so there's no specific reason to panic and the rate isn't outrageous.

The problem is caused by some other system (often SCOM) querying WMI-PA; when this happens, the service starts, processes, and then shuts down again -- leading to a huge bloat of system logs.

The solution is to set the WMI Performance Adapter Service to the "Automatic" startup type. This will stop the launch/shutdown cycle.

(Ref: http://lokna.no/?p=1430)