Buggy path finding pigmen slow down PC/Server and can lead to crash game.

I found this issue by creating piston press in nether and try to kill pigmen with this press. When i hit one pigman and came to piston press i saw that pistons slow down and pig man too. Big lag started. In one of my tries of finding this issue server suddenly stopped because of lag 60s.

So I have created simple testing world (attachement). There is wall in "plus" shape. In the middle is clocked note block for hearing slowing of PC. On the ground are 4 pigmen. Hit one pigman and go on the wall to place which persuade to move pigman to another sector. When they start follow you the game will slow down, you will hear slow ticking on note block. When pigmen reach closest point to you, your PC will speed up and note block will play a lot of notes in one second until it reach normal game clock.

video for:
16w05b https://youtu.be/wJ9GpW7Ri50 (working bad, hear note block)
1.8.9 https://youtu.be/85q-W1N0x00 (working ok, hear note block)