if you put a mob you tie it high to the fence, then remain stop, the mob starts moving slowy

Steps to reproduce this issue:

1. Grab fences, then build a vertical tower of 5 or more fences

2. Then, spawn a mob you like, (all mobs will affect this issue)

3. Then, tie up the spawned mob, and remain doing no moving, and observe the mob moving slowy

Expected result:

If tie up a mob to the tower of vertical fence, if remain stop the player, the mob will not moving slowy

Actual result:

If tie up a mob to the tower of vertical fence, if remain stop the player the mob will be moving slowy.