fps higher than monitor refresh rate makes mouse movement more responsive and consistence, that is why all pros aim for max fps, constantly losing 50% of avg fps every teamfight will make the game unplayable at any framerate
I went from having a stable 300 fps at high settings to the game being unplayable.
100 avg fps lower than before, with fps drops of 100+, even though I set all of my settings as low as possible.
All of my other games run fine with little to no fps drops, my pc has no overheating issues or anything.