Suffers from intense stutter all the time (every second or so, it 'hitches'). Vsync prevents the stutter from occurring in the menus, but has no effect on gameplay.

Graphical settings don't affect the stutter, neither does 'simulation quality'. It's certainly playable and completable, but without any gunfire -- the moment the AI goes on alert, the stutter goes through the roof, making the game completely unplayable.