I've been monitoring my task manager and the Hey! Cortana system process uses about 12-15% of my CPU resulting in a total idle CPU usage of around 30% whenever it is activated. Granted, I'm running W10 CP on my 1st/2nd gen Asus Netbook (single core, 1.5ghz max processor). So, I doubt the usage will be as significant on a more modern machine. I just thought it was good info to get out there. If you're using as ancient a machine as I am, you would do well to turn it off.
FYI, When I turn it off, the process goes away and my total idle usage falls to around 5-8%. So, it may also be using some other background processes.
FYI, When I turn it off, the process goes away and my total idle usage falls to around 5-8%. So, it may also be using some other background processes.