update: I have a second system with an i5 8600k and an Asrock z370 extreme4 board. After swapping some parts around, I noticed that, when using these configurations:
8600K + Asus mobo = stutters
8700k + Asus mobo = stutters
8700K + Asrock mobo = stutters
8600k + Asrock mobo = no stutters
I'm currently trying to do a BIOS update on the Asus board..