Explanation: I can move slightly faster if I am moving diagonally. Pressing W and D while looking slightly left (So my direction of motion is straight down the hallway) allows me to move down the hallway faster than if I was just moving forward with W. This is especially noticeable when sprinting.
Can it be repeated?: It can be easily repeated. Just move diagonally and compare the speed to moving straight. While sprinting I would observe how much of my sprint bar is used when moving straight vs diagonal.
Any other notes: If there is any moment in the game that relies on the player's movement speed being only so fast, the player could abuse or trivialize that moment in the game. While this issue may be mundane or inconsequential, I thought I would let you guys know that this occurs. All of my settings and input map is default. Move right and left are D and A. Move forward and backward is W and S.. I tested this in v0.5.7.1 and v0.5.7.5.