I think it's GPU related problem since when I play video in the background, all the lags are magically gone. Also, when I was on HS, the GPU load gets high to the maximum when the screen gets updated(yeah, it's abnormal too, but at least I don't get a laggy performance though QAQ).
Is there anyone suffering from the same problem as me? Or solved it?
For more detailed specs of my Hackintosh,
CPU : R5 2600 (OC to 3.8GHz)
M/B : AsRock AB350M Pro4
RAM : Samsung DDR4 8GB * 2
GPU : GIGABYTE VEGA 56 (the reference one, but the gaming one(w/ two fans) had the exactly same issue before on Mojave w/ ryzentosh)