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  1. Minecraft: Java Edition
  2. MC-162253

Lag spike when crossing certain chunk borders



    • Type: Bug
    • Status: Open
    • Resolution: Unresolved
    • Affects Version/s: 1.14.4, 19w39a, 19w40a, 19w41a, 1.15 Pre-release 1, 1.15.1, 1.15.2, 20w06a, 20w12a, 20w17a, 20w18a, 1.16 Pre-release 2, 1.16 Pre-release 4, 1.16 Pre-release 5, 1.16 Pre-release 8, 1.16 Release Candidate 1, 1.16, 1.16.1, 20w27a, 20w28a, 20w29a, 20w30a, 1.16.2 Pre-release 1, 1.16.2, 1.16.3, 1.16.4 Pre-release 2, 1.16.4, 20w45a, 20w46a, 20w49a, 1.16.5, 21w06a, 21w08b, 21w11a, 21w15a, 21w16a, 21w18a, 21w20a, 1.17 Pre-release 4, 1.17 Pre-release 5, 1.17 Release Candidate 1, 1.17 Release Candidate 2, 1.17, 1.17.1 Pre-release 1, 1.17.1 Release Candidate 1, 1.17.1
    • Fix Version/s: None
    • Labels:
    • Confirmation Status:
    • Category:
    • Mojang Priority:


      The bug

      I've encountered some sort of lag spike which I narrowed down to be a floating structure. This structure can be a single block.

      The lag spike seems to occur when I'm moving into the spawn chunks while an elevated block is placed on the opposite side of the spawn chunks. It does not occur in single player and occurs when the block is at Y96 or higher.

      To replicate what I did:

      • Create a default world with seed: -4952361208952771886
      • Place a block at x 143 y 63 z -371 and another block at x 144 y 63 z -371. This is the location to test for the lag.
      • Place a block at x 307 y 96 z -302. This will be the block to create the lag.
      • Set the spawn point to x 227 y 66 z -376
      • Walk back and forth over the two blocks you placed earlier.
      • If you see a stutter, feel free to remove the block at x 307 y 96 z -302 and check again. Lag will be gone.

      I do not know if this is seed specific but this is the seed my world is on and I've been testing with that.

      I cannot attach the video as the file size is slightly too large but you may watch it here: https://youtu.be/jmtq3jcXujo

      I should note that it is not specific to my PC. It occurs on other clients on other devices.

      Code analysis

      Code analysis and further explanation by Philipp Provenzano can be found in this comment. There also exists a Fabric mod that fixes this issue: comment.


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              slicedlime [Mojang] slicedlime
              Tencryn Tencryn
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