I used to play Tom Clancy's Rainbow Six:SIege at 70FPS+ with ease with my old monitor (1280x1024@75hz). After getting the new one (1920x1080@60hz) my performance got really poor.
My specs are
Processor Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz
Video Card NVIDIA GeForce GTX 1050 Ti
RAM 16 GB...