Hi Mike,
Audirvana for windows does not have the 'system optimization' option for now. Will it be incorporated in a future update? Time will tell. It is unclear to me as to what extent Apple will allow a 3rd party software to shut down non-essential activity/processes in its OS. I haven't used an Apple computer in a couple of years but as I understand Apple OS is more of a closed system which makes it safe against viruses/malware but also allows less 'tweaking' compared to windows OS (correct me if I'm wrong).
So I believe that for the time being Fidelizer does not interfere with what Audirvana windows can do.
Edit: Also, Fidelizer is only available for Windows OS.