Dimension Leak Fix

Mod

by Bahanos

Fixes memory leaks when switching dimensions. Mods like Collective, AmbientSounds and Create retain old worlds in RAM - this mod cleans them up automatically, recovering 2-4 GB per transition.

Type

Mod

CurseForge Downloads

238,474

CurseForge ID

1472850

Modrinth Downloads

36,609

Modrinth ID

nT8BgIrU

Last Updated

Oct 17, 2026

Description

Every time you travel between the Overworld, Nether, and End, your client creates a new ClientWorld. The old world should be garbage-collected, but several popular mods accidentally hold references to it - causing it to stay in memory forever.

After just a few dimension changes, this can eat 4-8 GB of RAM, leading to lag spikes, stuttering, and eventually crashes.

Dimension Leak Fix automatically detects dimension transitions and surgically breaks these retention chains, recovering 2-4 GB of memory per transition.

What it fixes

Source	Problem	Impact
Entity references	Entities in the old world hold a `.level` field pointing back to it	~200 MB per transition
Collective	`BlockEntityData.cachedBlockEntities` retains old worlds through nested WeakHashMaps	~1.2 GB per transition
AmbientSounds	AirPocketScanner thread holds thousands of ChunkSections as a GC root	~1.4 GB per transition
Create	Renderer caches hold references to old world data	Variable
Chunk storage	Old world's ChunkManager retains all loaded chunks in memory	~1-3 GB per transition

How it works

The mod uses a two-phase approach:

Phase A (instant): When you change dimension, the mod immediately detaches entity references, flushes Collective caches, stops the AmbientSounds scanner thread, detaches Spark command senders, and invalidates Create's renderer.
Phase B (3 seconds later): The mod clears the old world's chunk storage array and entity sets. This is delayed to avoid interfering with the renderer during the transition.

Compatibility

Client-side only - does not need to be installed on the server
Works with or without any of the mods listed above - the mod detects what's installed and only applies relevant fixes
Tested with 200+ mods including Iris, Sodium, Distant Horizons, Create, Collective, AmbientSounds

Log output

The mod logs everything it does. Example output after a dimension change:

[DimensionLeakFix] Dimension change detected, cleaning up old world...
[DimensionLeakFix]   Entities: 131 world references detached
[DimensionLeakFix]   Collective: 1 cache(s) flushed in cachedBlockEntities
[DimensionLeakFix]   AmbientSounds: scanner stopped (3 fields cleared)
[DimensionLeakFix]   Create: renderer cache invalidated
[DimensionLeakFix] Phase A complete (137 operations)
[DimensionLeakFix] Phase B scheduled (3s delay)
[DimensionLeakFix] Phase B: releasing old world data...
[DimensionLeakFix]   Chunks: 2809 slots released
[DimensionLeakFix]   loadedChunks: 2809 entries cleared
[DimensionLeakFix] Phase B complete (2810 references released, ~3706 MB freed)

Used in the Legends Reborn: Medieval modpack.