It's more about singe core CPU speed what is limiting the game, not the GPU, so don't just buy a new graphics card and expect miracles.
While I can run this at native 2560 x 1440 (4K) @ 165 refresh with about 140 FPS, in some scenes the FPS would drop under 45 FPS, also if I move away quickly the camera to scout, in certain regions.
If you want to keep very high FPS all the time, a far better single core CPU is needed (there's none, unless you can go above far above 5 MHz with lab level cooling)
1080 GTX or similar or better can run this GPU-wise at 4K just fine, and when the frame rate drops, the bottleneck is still the CPU.
60 FPS is not needed, there are no fast moving scenes or objects here. 30 FPS is fine and the system coolers can slow down at 30 FPS enough to reduce background noise a lot, as well the power consumption is less.
There could be a catch here though: I have FreeSync enabled and working in "fake fullscreen" (aka windowed fullscreen mode), so I don't have stutter even when the FPS goes down to about 20. Without FreeSync/G-Sync could be annoying if the FPS goes down, but that will happen anyway no matter if you limit frame rate or not.
Don't forget to google and learn about each graphics options, if possible from a good source like Nvidia, because one can still have good looking graphics on low.
Set shadows to very low, but textures try to keep at medium (maybe even high) while giving up on other parts. Lighting, effects and shadows are the most demanding parts, that's why hardware based Ray Tracing will help a lot, but will take few years until the price of those will be low enough to be adopted mainstream.
