[read]

Why is Esc-/ easier than Ctrl-f (or Ctrl-s in Emacs)?

Esc requires you twist your entire left hand sideways up to hit the Esc, whereas Ctrl requires you move only your left pinky to hit the Ctrl.

Ctrl is more efficient.

[Curmudgel]

Efficiency really depends upon the keyboard you're using. If you use a keyboard with thumb clusters, the control and meta keys are under your thumbs and you don't need to twist your pinkies at all.