For a recreation, i didn't really do anything out of the norm, just created a new world and encountered this bug.

I just updated version using the MC launcher and created a new Survival world and with around 3-4 hours of playing in it I've noticed chunks not loading in yet surrounded by normal loaded chunks. They load in after a couple of seconds of looking at them but this causes quite a high lag spike that lasts 3-4. For me the game is still playable but it has been quite a problem when dealing with hoards of mobs.

Thanks