Severe Lag at Specific Locations When Using CustomNPC-Plus (Freezing NPCs Temporarily Fixes It)

[zeng-github01]

Issue description:
When I enter specific locations in my migrated world, the game experiences extreme lag (massive FPS drop and near-freeze). After testing with VisualVM, it appears that NPC-related logic is consuming a large amount of resources in those areas.
If I use the NPC Wand and enable Freeze NPCs, the lag is immediately and significantly reduced. This strongly suggests that the issue is related to NPC AI, pathfinding, or collision processing.

Additional Notes
• This world was migrated from Minecraft 1.6.4, so some NPC data or NBT structures may be outdated or incompatible.
• The lag only happens in certain chunks, which may contain old NPCs or corrupted NPC data.
• Freezing NPCs consistently removes the lag, so the problem seems tied to active NPC behavior.
• This issue may be related to the previously reported NPC Spawner bug that caused severe lag. The symptoms are almost identical, so I am not sure whether this is a derivative or secondary effect of that problem.

Expected Behavior
NPCs should not cause extreme lag when entering specific areas, even in migrated worlds.

If crashed, link to crash report (use a site such as pastebin):

Versions:

• Minecraft: 1.7.10
• Forge:
• CustomNPC+: 1.10.2

Can it be reproduced with just CustomNPC+? If not, list the other mods required to reproduce the issue.

[zeng-github01]

@KAMKEEL How can I help you fix this problem? I'm willing to cooperate if possible.

[KAMKEEL]

@zeng-github01 MC 1.6.4 or CNPC+ 1.6.4

[zeng-github01]

@zeng-github01 MC 1.6.4 or CNPC+ 1.6.4

I'm using a map that was converted from version 1.6.4 to 1.7.10; the original map used CNPC.

[KAMKEEL]

@zeng-github01 MC 1.6.4 or CNPC+ 1.6.4

I'm using a map that was converted from version 1.6.4 to 1.7.10; the original map used CNPC.

I can figure out where the lag occurs if you use a Profiler.

https://www.curseforge.com/minecraft/mc-mods/spark/files/4271867

Use that MOD and run /spark profiler then after experiencing heavy lag do /spark profiler --stop and send me the log here

IF ITs Client Lag. you need the mod on the client side (not server) and do /sparkc profiler and then /sparkc profiler --stop

[zeng-github01]

@KAMKEEL https://spark.lucko.me/nQrG718MgZ

And this https://spark.lucko.me/UiCaap4b8m

[zeng-github01]

Confirmed to be the same as before. The Spawner NPC is being generated infinitely for unknown reasons, causing lag in collision volume calculations.

[zeng-github01]

@KAMKEEL I have identified the root cause of the bug. For some unknown reason, the generator failed to detect that the generation process had completed, which led to this issue.