Turning/looping with killer

This is something I probably should have asked a while ago, but how does using a and do while a killer affect move speed? Like say a survivor is looping me, should I be using a or d while pressing w to go around the object or a corner, or is it better to only use my mouse to turn? I feel like I'm actually going slower than survivors sometimes. 

Bonus question, how does turning with hillbilly work with a and d compared to using the mouse? If I use the keyboard does it make him turn as fast as he can? What about with the mouse?