MC-168419Massive frame drops caused by light update while crossing certain chunks
The Bug
Duplicates MC-162253. Why you always find your own ticket duplicate after you create one 
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) |
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. 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).
Notice massive lag.- Notice root.gameRenderer.level.light_updates takes too long in the game log.
- Move from chunk (0, 1) back to chunk (0, 0).
Notice little lag.
- Set your Render Distance to 4.
- Move from chunk (0, 0) to chunk (0, 1) again.
- Notice little lag.
- Move from chunk (0, 1) back to chunk (0, 0) again.
- Notice little lag.
Linked Issues
![[Mod] SPGoding](../../../data/avatars/users/44622.png){kind=small}
Created Issue:
Massive PPS drop
The Bug
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.
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) 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. 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).
- Move from chunk (0, 1) back to chunk (0, 0).
- Set your Render Distance to 4.
- Move from chunk (0, 0) to chunk (0, 1) again.
- Move from chunk (0, 1) back to chunk (0, 0) again.
Attachments4
MassivePPS dropMassive FPS drop
Massive FPS dropMassive frame drops caused by light update while crossing certain chunks
The Bug
Duplicates
MC-162253. Why you always find your own ticket duplicate after you create oneMoving 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) 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. 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).
- Move from chunk (0, 1) back to chunk (0, 0).
- Set your Render Distance to 4.
- Move from chunk (0, 0) to chunk (0, 1) again.
- Move from chunk (0, 1) back to chunk (0, 0) again.
duplicates
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.