Controller Input Delay/Lock

[Demolish]

OS:
Windows 10 64-bit, Linux (using dxvk)

Description:
Controller input delay and buttons being 'held' when FPS drops.
During raids, this leads to the game thinking buttons are being held down for seconds after they've been pressed. This often leads to the game pressing skills on its own and walking player off the edge of the arena.
Keyboard and mouse input remain unaffected, this only affects gamepad input (wired as well as bluetooth).

Drivers have been reinstalled multiple times, along with fresh install of Windows, and then tested again on Linux to exclude driver issues.
The issue also exists on DX9 although to a lesser extent as long as framerate is capped and has been persistent since 2.0 (A Realm Reborn). However, as the DX9 client will be discontinued in Shadowbringers this game will be unplayable on DX11 with a controller.

Steps to reproduce:
Easiest to reproduce on DX11 client with FPS unlocked (still occurs with FPS limited on both DX9 and DX11 though mainly in GPU intensive scenes). Happens regardless of window mode (fullscreen, windowed, borderless).
Play with controller (Xbox 360 and DS4), disable fps limiter, enter a raid - doesn't matter which. Alphascape v4 and v3 (Savage) are pretty obvious to test with when your character walks off the edge despite letting go of thumbstick seconds ago.
Alliance raids (Stormblood raids especially) are good test cases too.

Additional method to reproduce framerate drops to test the controller input delay/freeze is to zoom in on a Warrior spamming Decimate, FPS will drop significantly (almost half) no matter the system spec.