Walking up stairs while having Auto-Jump enabled is noticeably faster than without, and it sometimes also goes so fast that the game abruptly stops you from moving for a split second.

To reproduce:
Create a staircase with 20 or so stairs (it becomes more noticeable the bigger the staircase is). Make sure you have free air space above so you don't bump your head on the way up. Try walking up the staircase both with Auto-Jump enabled and without, and observe the difference.