[FFaust]

To me, smoothness of the inputs or of the car simply means being progressive, it does not mean being slow (car or inputs). For instance, if applied to braking, it could be equated to operating a "valve", not flicking a "switch".

Everything is about balance: Higher speed means higher kinetic energy. The car has a mass and therefore inertia (wants to stay in motion in its direction of travel, or in its current steady state). Braking, accelerating, or turning all require a change of path or speed, and therefore are affected by this inertia. Smoothness will allow to change this path or speed while remaining within the physical limits imposed by the equipment (suspension, tire grip, weight, etc.), and allow the equipment to work as designed.

The proper/fastest line will also be the smoothest. Yeah, it might be a heck of a ride, but the car will be within its limits.

With higher speeds come higher forces and shorter times. Smoothness and balance are still required, but the margins melt away.

Hope this makes sense as written.