I recently came back to the game and immediately noticed input lag through mouse/keyboard. Turns out the -dx9 startup command solved this issue. But now it's hard to ignore the smoothness dx11 brought to the gameplay. I've checked vsync settings both in-game and through Nvidia's control panel yet input remains sluggish with these off. I don't have this issue with any other game running dx11. For now I will continue to run dx9 due to its responsiveness and snappy movement, but hopefully this can be looked into by development.