Same here, alt and tabbing out of the game, even though my system isn't showing signs of being taxed, I find scrolling in Firefox shows the same symptoms of micro stuttering, its as if every second frame is skipped and yet my monitor is running at 144hz. Closing the game, instatly scrolling becomes silky smooth again. i7 4770k @ 4.2 16gb ddr3 ram 1080ti gpu using latest drivers (always updated, never makes a difference) Win 10, latest updates. Oddly i found disabling some cpu cores makes no difference to D2's framerate.