The Bug
Duplicates MC-162253. Why you always find your own ticket duplicate after you create one π
Moving from certain chunk to another chunk with certain Render Distance in the certain world will cause massssive FPS lag. I don't know what causes this, but I can provide as much information as I can.
Here's a table with several sets of Render Distance, source chunk, and destination chunk which cause massive FPS drop. I believe the spawn chunk is (1, 5).
Render Distance | Source Chunk | Destination Chunk |
---|---|---|
2 | (0, 0) | (0, 1) |
2 | (0, 8) | (0, 7) |
2 | (1, 8) | (1, 7) |
2 | (2, 8) | (2, 7) |
2 | (3, 8) | (3, 7) |
2 | (-3, 8) | (-3, 7) |
2 | (-2, 8) | (-2, 7) |
3 | (-4, 3) | (-3, 3) |
3 | (-4, 4) | (-3, 4) |
4 | (-5, 1) | (-4, 1) |
4 | (-5, 2) | (-4, 2) |
5 | (-6, 0) | (-5, 0) |
6 | (-6, -3) | (-6, -2) |
7 | (-7, -4) | (-7, -3) |
7 | (-6, -4) | (-6, -3) |
8 | (-9, -4) | (-8, -4) |
8 | (-8, -5) | (-8, -4) |
h3. To Reproduce
Download the attached
World File.7z
. Extract it to.minecraft/saves/
. (The whole world is too large to upload, so I deleted many regions.Β The bug is still reproducible with the attached world file.)Enter the world.
Set your Render Distance to
2
.Move from chunk (0, 0) to chunk (0, 1).
β Notice massive lag.
β Notice
root.gameRenderer.level.light_updates
takes too long in the game log.
Move from chunk (0, 1) back to chunk (0, 0).
β Notice little lag.
Set your Render Distance to
4
.Move from chunk (0, 0) to chunk (0, 1) again.
β Notice little lag.
Move from chunk (0, 1) back to chunk (0, 0) again.
β Notice little lag.
Linked issues
Attachments
Comments

I checked this out and can confirm that this occurs for me too. I also didn't know there was a log so thanks for that.
The lag spike will occur crossing -9, -4 into -8, -4 all the way up to -9, 11 into -8, 11 when render distance is set to 8. A total of 15 chunks along the Z axis.