I noticed my FPS drop to 52-54 during combos even though I get 59+ stable FPS during benchmark on any graphics preset, including low or ultra.
Dynamic Thread Priority
Apparently, MK1 uses e-cores on intel CPUs, which leads to stuttering.
It is possible to disable e-cores in BIOS (and it worked for me), however having to do so just to play MK sucks.
There is a way around it, however.
You can download Process Lasso and either disable e-cores for the MK process in the CPU affinity->always section, or, which is a better way, disable Windows dynamic thread priority boosts, as seen on the screenshot.