Throttling is set but backup is not running when it is presenting the issue.
The game (World of Warcraft) is not using any SQL components. It's self-contained within its own folder. It is quite I/O read intensive obviously loading its graphics.
When I check in performance monitor to see what it's doing it is guzzling cpu and just accessing the VEB database, not even massive read or write operations. It's not constant but can spike up quite high.
I'd just assume changed block tracking if I was doing massive writes but since I'm doing mostly reads it struck me as very odd behaviour.