Nostalrius Begins - Quality wow vanilla realm (1.12)

Hello, I have a little problem my with game.
I have installed WoW Classic via Nostalrius installer, everything is working... but there's small microstuttering every half-second.
Game is working fine - 60 fps constant, everything maxed, 1920x1080 resolution and no lags at all (50ms).
I've tried to disable Vsync and other options one-by-one to determine that maybe one of those are causing this stutter, but unfortunatelly nothing helped.
All new games I have on my PC are working flawlessly (even retail WoW which I have) - problem only occurs in classic WoW.
Any help will be really appreciated!

try this if you are using windows

Control Panel > Power options

Select High performance option, and ensure that under Advanced Power options PCI 'Link State Power Management 'is set to OFF.

Basically, windows cucks your GPU pci express slot and this option is only useful if your saving battery power on a laptop.

same thing is occuring to me rather frequently. I can play mgs5 and the witcher 3 maxed out with like 200fps but vanilla wow is giving me stuttering and frame drops.