I noticed that whenever I start iTunes and then close it my little Windows cpu gadget reports approx 10% usage for a good 30 seconds afterwards. I checked the process a few times and opened task manager. It is cortana background task host that always runs approx 10% in the aftermath of iTunes being closed. Like I say it doesn't last long before going back to 0%. But why would cortana background task host be kicked into life by iTunes? We have another living room PC which is so weak but I tested same process on this and it doesn't really happen, cortana background task maybe runs 10% for a couple seconds.

the difference between the two machines aside from a huge power differential is the machine it happens on has about 4000 songs and locally stored in the iTunes library. The weak machine it doesn't happen on has no songs locally stored, we just stream music in iTunes using the iCloud music library