same for me: had some huge stuttering and frame drops. Tried everything too and finally i looked at Windows game settings and noted that audio recording was enabled. I disabled it so and game is running well since: no frames drops anymore. So try to disable Game audio recording if it is enabled as actually it worked for me.

hi folks,

have some frame drops too until i disabled on Windows 10 in system game settings audio recording;
background recording was disabled yet on my system but not audio and disabling it seems to have magically resolved all my stuttering and frame drop issues.
Hoping this tip will help you too.