could be unrelated to the changes, I tried this on my PC with locked 60 fps. What this flag does is that it moves the reads of streamed audio to the game thread which in theory is bad. If you are on a fast SSD it might not be that slow, but on a HDD it might cause alot of issues.
Are you running the game on a SSD? (our log tells me that you do).
Could there be issues with said drive? Perhaps try move the game to another disc if possible since the original issue could be due to this.
My guess is that your perf issues might be related to the original issue.