Is there any simple way to show how long a specific PID instance has been active?
I know that Process Explorer will show this, sort of.
If you run it, right click on a process and choose
Alternatively in Process Explorer you can click
You might need to do your own math on the individual threads within that process (again the threads tab) and the current date/time to get a true "how long" answer.
Using the Powershell Get-Process cmdlet: