XB1: Mobs do not despawn outside 128+ limit.

Hello
I built a dispenser in creative filled it with different mob eggs zombie, skeleton, pigman and let it run for a while. All mobs drop into water, for the effect.

Moving away 128+ in any direction and all the mobs should despawn.
However they do not, also not if I go to Y:200.

Made a video of that.

I also noticed a increased lag when mob cap was reached, maybe it is because all mobs tried to move and not stationary i.e not a normal test/situation.

I guess this also explains why everything is slow in spawn speed, ~33%, I mean.

I seen this a while now but TU45, TU46 and TU47 but I always thought that I was inside the 128 range. not

Edited/amended
I guess I found another reason why pc-players moved to Console edition, mob farms died out because of mobs stopped spawning in a mob farm. As this is a PC intended behavior. With no despawning if picked up item.
However since I am sure about this bug and slimes do not pick anything up I made a video about slimes not despawning outside 128+ blocks aswell.
I guess if we want a mob farm it must be in a flat world with no caves and night all the time, so that no mobs die and litter the minecraft world.

see the attached video about slimes in the same location.

Regards,
Marcus and Ariana gt ariana gaming