If you are standing on a piece of bamboo when it grows if you crouch you walk at the same speed as if you were standing up even though you still receive the benefit of not falling off the block.

 This also affects chorus fruit and trees

Also, before you say that this is a copy all the others that I found were just about bamboo growing into you or being able to jump in bamboo. They were also all duplicates of an invalid bug report so double-check that saying this is a duplicate is the right decision.