It has come to my attention that the game loads input icons synchronously any time it sees input on keyboard/mouse or gamepad.
This means if you are using a gamepad generally but you hit a button on your keyboard -- hitch. If you use keyboard/mouse but hit the analog stick -- hitch.
My own mod framework (Special K) is capable of working around this by preventing the game from seeing input events on devices of your choosing.
Extract to FFXV's install directory, done.
Delete dxgi.dll, the Version and logs subdirectories (these are all part of Special K, not the game)
Thread Rescheduling Details < 0.9.9.8 >
This (final?) update includes options that fix thread scheduling on the most important (least important, actually) threads.
Having these scheduled incorrectly is responsible for:
Increased load times (as is SteamAPI, as is anti-debug ..... Square-Enix hates us)
The thread priorities for VSYNC Emulation Thread and SwapChain Flip Thread are set way too high by Square Enix and are making it impossible to distribute a workload across your CPUs. This is known as starvation. You simply have things the game needs to be doing with the CPU that it cannot because Square Enix has too many threads running at a ridiculous priority level that is not generally useful for rendering.
Lower those thread priorities to Highest or Above Normal. I would suggest everyone do this, I even do it and I have plenty of CPU cores.