Game is in fullscreen.
Disable hardware antialiasing to get a feel for the mouse movement without it enabled.
Enable Hardware Antialiasing to the highest level.

• There is a noticable delay in mouse input from your mouse to the screen. The higher the level, the stronger the effect (unless placebo).

To test if this is attributed to other settings, I did the following:

1. Set preset quality to Poor, apply.
2. Enabled all settings to Extreme one by one, starting from top to bottom.
3. Move my mouse rapidly during each and every set to Extreme, to test for input lag.
4. Enable Hardware Acceleration
5. Move my mouse rapidly, I now notice a gameplay affecting input lag.

The higher the detail/level set of Hardware Antialiasing, the higher the effect. This may be placebo.
Foliage Smoothing does not have an effect on the input lag.

Setting all settings to low using the preset, then to extreme with Hardware Antialiasing turned off shows no difference in input lag, meaning this is not tied to other settings.