Alix Albert

Yup, this happens to me frequently, and not only in 1.13.2 – but never when I am actually in the game, actively playing it.  It happens when I leave the game in the background while I am doing other things.  It doesn't really matter what I do as the player at the time – I might be sitting in my inventory, waiting for spawns at a mob grinder, or I might not even be in a world and am just sitting on the splash screen.  This might be a Java problem, and might be related to how much memory Java is chewing up; my machine is usually under quite some memory load.

Contrary to @cjburkey01 on my machine (an elderly MacPro) 18w47b runs better than 18w47a, which was nearly unplayable, it lagged so bad, and not only on chunk loading.  But there are still serious chunk loading problems now, and glitches that seem induced by lag (I fell off a tall column when mining straight down – I saw myself glitch to the edge without having moved of my own accord, and then I fell off when I next hit the block with my pick).  Upon first entering my test world I still hang in a void for nearly a minute (see only the sky and what's in my hands, no terrain).  FWIW 18w44a ran best for me out of the current snapshots.