I just started the game and had micro-stutterings during even the first game scene: FPS was quite OK (~60FPS) but every 1 or 2 sec a stutter would occur, even on lowest settings (which would give higher constant FPS).
After medling with VSYNC options without success, trying to set CPU affinity onto only 2 CPU cores (hello Subnautica :)), I finally solved it after seeing the game was running with "Background" CPU priority, which is utterly stupid (and I don't know where it comes from). I set it at "Normal", and micro-stutters are gone. (Process Explorer is your friend for this)
TL;DR: chech the CPU priiority of the game process, and check it is "Normal" and not bellow, "it worked for me" (c)
Gonna try this out to see if it works. I´ll let you know. Thanks!