The two balls are released simultaneously from rest and have equal initial and final heights. The High Road remains at a constant height but the Low Road is a longer path with a changing height. Which path is faster?

The time required for each ball to traverse its path is the horizontal displacement divided by the average horizontal velocity. The High Road and Low Road have equal horizontal displacements, but the Low Road has the greater average horizontal velocity. Why? Because the normal force of the Low Road track produces an instantaneous horizontal velocity that is always equal to or greater than the instantaneous horizontal velocity produced by the normal force of the High Road track.

Thus, the Low Road is the faster path. This outcome holds true for any lower path shape, no matter its length, as long as the ball does not slip or leave the track.