Dimension Leak Fix

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.