Essentially, entities that are further away from the player appear to have broken, choppy movement and seem to teleport around. Keep in mind that this is only an issue in the latest beta.
How to reproduce: There are many ways to do this. My way of doing it is shooting an arrow and viewing it fly far away. You might notice its movement getting worse.
Linked issues
is duplicated by 12
MCPE-109237
Mobs except Enderdragon having stuttery movement
Resolved
MCPE-115582
Mobs move erratically when they get drawn
Resolved
MCPE-118848
Entity movement is jittery and stutters from a distance.
Resolved
MCPE-120664
Mobs laggy move
Resolved
MCPE-123164
Moving Entities (Villagers, Cows, Sheep, Etc.) Are Really Choppy
Resolved
relates to 2
Attachments
Comments 23
I believe this is caused by the `"minecraft:conditional_bandwidth_optimization"` component, which "makes sure level event packets only broadcast locally", which drops ticks for better server side performance.
https://bedrock.dev/docs/beta/Entities#minecraft%3Aconditional_bandwidth_optimization
I do notice the choppiness though, so I will upvote.
ambient's comment mentioning server-side performance reminded me that I've experienced choppy movement off-screen. So I think this is not just a rendering issue, but actually an entity ticking issue that negatively impacts the game's functionality.
Here is what I mean:
During the 1.16 betas I built a contraption to test the changes to vertical despawn distance. It consists of a zombie spawner high in the air over a platform that flushes zombies down a drop shaft. Every 10 blocks of the drop shaft there is trip wire attached to command blocks. Those command blocks, when powered, place redstone blocks to activate a system of redstone lamps. Other command blocks reset the system soon after each display. This contraption allows you to stand by the zombie spawner to get frequent mob spawns and observe the lamp display for a readout of how far the zombies fall before despawning. The output is fairly reliable on my Windows 10 PC, but on my iPhone 8 it is not reliable at all. It seems that when the zombies are falling outside the player's FOV, their positions are not updated often enough to consistently register collisions with tripwire that is placed every 10 blocks.
Here is the test world:
[media]
UPDATE: Another ticket, MCPE-94945, earlier raised the suspicion that unreliable mob updates farther from the player could lead to random despawns due to mobs not being saved to chunks. I have resolved that ticket as a duplicate of MCPE-21416 where we track the issue of random despawns generally, but the hypothesis seems at least on the surface to be related to the issue tracked here. If, indeed, optimization coding causes mob ticks to be skipped during times of high server/CPU activity or storage access such as loading and saving chunks, that might begin to explain the many anecdotes of mobs disappearing after long-distance travel and use of nether portals.
affects 1.16.100. It seems that this also locally affects item sprites before they hit the ground. They appear very jittery while in motion in 1.16.100, but this does not happen in 1.16.40.
It’s been a few years now and I think this is an easier fix as LightKnight has demonstrated. Having observed these years without any fix for this issue I would like to bump it as this issue is really annoying. Is there some particular constraint keeping the devs from fixing this issue?
Confirmed based on attached video.