Setting anything to real-time priority is a really bad idea. In a word, "foolish" (his word, not mine):

https://devblogs.microsoft.com/oldnewthing/20100610-00/?p=13753

And then there's this:

"You should almost never use REALTIME_PRIORITY_CLASS, because this interrupts system threads that manage mouse input, keyboard input, and background disk flushing. This class can be appropriate for applications that "talk" directly to hardware or that perform brief tasks that should have limited interruptions."

from https://docs.microsoft.com/en-us/windows/win32/procthread/scheduling-priorities?redirectedfrom=MSDN

TrackIR is constantly gathering control input from the camera, and is completely opposite "performs brief tasks".

Of course, I'm sure people trying to get a game running better on their computers by trial and error know better than this guy...probably at least one video on YouTube that says this is a good idea.