With a semi-efficient riding posture:
Inclined back ~45 degrees, with weight taken on slightly bent arms/hands and feet as well as the saddle, the rider gets relief from pressure on the seat, road noise and shocks pass 'back' by rotating the hips 'up and back' from the shoulders. A more or less narrow, supple, conforming, but smooth and firm saddle gives the best combination of support/comfort ~ typified with the Brooks B17/C17/Pro style saddles. Narrow in the nose, wide at the rear, and will 'take' a shape that actually *fits* you over time.
The rider also reduces the air-drag that limits higher speeds for lower efforts by this forward leaning posture.
On the other hand, 'comfort' bikes (or normal bike, set up incorrectly) have a (near) vertical back posture, with negligible weight on the hands, usually little force on the pedals and all the weight on the seat. Any road noise/shocks go right up the spine. Saddles with lots of padding, springs, suspension seatposts etc are needed to make this bearable, but this type of saddle can only do so much, and are generally horrid for all sorts of reasons. You also have such a large 'sail' area that high speeds for modest power becomes unreachable.