I seem to have found a solution!
had problems running doom 2016 and eternal, my pc specs can run the game on high with medium textures, and I was having trouble with my mouse, cpu reach 100 in game but on task manager not above 30%.. i used in-game benchmarks and stats..
After seeing some sites and stuff I got to the following solution (at least for me)
DIsable Hyper thread for intel users and for AMD something called cpu core boost
I DISABLED it... and doom returned to its former glory of 60 fps..
those with higher pc specs than mine (fx 8350 16gb ram gtx 970) with the same problem, search on your MB and CPU about this feature.. I guess its mostly used for programs that need a lot of proccesing, since my pc is for gaming, I disabled it and now everything's ok.
hope I helped someone, because I almost lost it!