Good Grief! I have to investigate more about performance issues. Have you experienced a Framerate drop below 60 FPS? If you have, what screen/biome/menu were you on when it happens? Also, can you tell what your hardware is? System requirements of this game are: Windows 10 64-bit; IntelCore i7-7700 3.6GHz; NVIDIA GeForce GTX 1060 6Gb; 16Gb RAM. 1Gb Storage.
D-Input gamepads sucks. Sony has an exclusive copyrights for D-Input technology, so Epic Games company is not allowed to implement the support of D-Inputs into the basic setup of Unreal Engine.
About different visuals for the disabled Menu Buttons - I could do it, but it is no sense to waste the time for making something like this and remove it later when the menu option be implemented.