Hasan Majid

Happens to me with a world of 262.1MB ( but doesn't happen with a world of around 200 MB ).

In my experience, this happens on my laptop and Switch, but to a way lesser extent on PC.

Sounds seems to take a while to load in, then once have been played once - they play instantly when triggered again.

MaLu is right - if you ignore the error then back out, the world would've uploaded anyway.

i think this is intentional

An example of infinite loading screens (occurs on Switch and Mobile, probably a CPU/IO problem). which occurs after leaving the game on the title screen for a few minutes.

The loading screen stops after a few minutes, but may start again when a world is loaded. 

 Block Sound Lag.mp4

Especially in large worlds, block sounds can have a huge delay and all play at once a few seconds later. In smaller worlds sounds could play shortly after they are suppose to. This only applies to new sounds (sounds that haven't been played upon load on the world).

Eg: A dirt block is broken and a few seconds later, the grass sound plays, if it is broken again the sound plays instantly, but if you go to break a stone block, that sound would have a delay, and then play instantly next time it is broken.

An example of infinite loading screens (occurs on Switch and Mobile, probably a CPU/IO problem). which occurs after leaving the game on the title screen for a few minutes.

The loading screen stops after a few minutes, but may start again when a world is loaded.

Happens to me sometimes on the main menu screen when I click "Play" or any other option, then I have to close the game and then the "Software error. Closed software" error pops up on the Switch home menu.

This is intentional. You can only get a maximum of seven levels back according to the wiki:

When the player dies, they drop experience orbs worth 7 * current level experience points, up to a maximum of 100 points (enough to reach level 7), and all of the other experience vanishes. If the gamerule keepInventory is set to true, the experience is kept even if the player dies

Edit: In version 1.16.20 and 1.16.21 the problem seems to have moved; players can now move around normally with chunks generating for them (on the host switch it can still be somewhat slow, but on other devices in the world chunks load fairly fast).

The problem occurs when autosaving starts, a variety of things can occur with the severity depending on your world size and simulation distance:

Block lag, chunks not loading (causing empty voids), lighting not loading, entity and mob jittering/lag.

 
Table for my large world

The duration of the autosaving also contributes to the severity of the lag, if the autosaving is short (less than 10 seconds) barely any lag happens, but if the autosaving is lengthy (1+ minutes) lots of lag occurs.

@Ryan Ashburn, it crashes when I press the home button (and then freezes the whole Nintendo Switch).

Yeah when setting the simulation distance to 4, chunks can actually load but you can still outrun their loading speeds (issues still occur),

This is more prevalent when the game is autosaving (along with block lag).

The amount of players in the game (at four simulation distance) doesn't seem to make a difference in terms of world speed (comparing single player to multiple players).

EDIT: I might try and make a creative copy then "/kill @e" to observer any possible changes

A work around I have found is to set the simulation distance to 4, which makes the problem less severe, although chunk loading can still be a bit slow.

Not tested 1.16.10 although yet.

A test of what happens with 3 players in a 110MB survival world (14 chunk render distance, 8 chunks simulation).

With one player in the world it was fine, with two players the game started to slow but was manageable, and with three players there was extreme lag everywhere (the loading bar in the centre of the screen was me trying to open my inventory).

Edit: Yes this was the actual framerate in realtime not just the video.

According to my testing, split screen seems to have the same effects as online multiplayer (fine in smaller worlds, bad in larger worlds), will need more testing to account for the fact that render distance is paired back in split screen multiplayer.

Do you have [Enable Content Log GUI] enabled in profile in settings?

Edit: I feel like (on switch atleast) moving the game to the internal storage (not micro-sd card), slightly sped up chunk loading, but we have no way of testing that.

What's weird though, is on switch save data can only be on internal storage.

I'll test local multiplayer soon, although I only have three (pairs of) controllers.

It seems that local multiplayer exihbits the same problems as (online) multiplayer.

After more testing, I am certain this affects large worlds more (tested on switch and windows 10, 120MB survival world yet again, v1.16).

Admittedly, copying the world, then deleting the original and playing the copy did slightly speed up chunk loading (this clip is the copied world).

In smaller worlds, chunk rendering gradually slows down when flying for a while, but here on the large world it slows instantly.

@Auldirck, the multiplayer was mentioned because when it is another player joins a (large) world, chunk loading becomes incredibly slow (or ceases to stop) making even walking hard.