LazyRAM

LazyRAM

NOTE: Requires Fabric API on fabric

LazyRAM is a fully automatic, client-side memory optimization mod for Minecraft 1.21.1 NeoForge, Quilt and Fabric.

It is designed to reduce unnecessary RAM overhead by compacting, deduplicating and retiring several memory-heavy Minecraft client structures.

There is no menu, no HUD and no keybinds. LazyRAM works automatically in the background and does not reduce your render distance or graphics settings.

What does LazyRAM optimize?

LazyRAM works directly with several internal Minecraft memory structures.

It can:

• Deduplicate model variant strings.
• Deduplicate identical BakedQuad vertex arrays.
• Compact baked-model face lists and directional face maps.
• Reuse identical model face lists instead of keeping unnecessary copies.
• Deduplicate collision and occlusion VoxelShapes.
• Deduplicate VoxelShape arrays used by block-state caches.
• Replace repeated 6-value block face arrays with shared canonical arrays.
• Compact BlockState neighbour lookup data into a shared indexed representation.
• Reuse empty DataComponent patch maps.
• Cache and reuse multipart block-model predicates.
• Deduplicate equivalent multipart baked models.
• Automatically discard temporary optimization lookup caches after they are no longer needed.

The goal is not to remove game data, but to avoid keeping multiple equivalent Java objects in memory when the same immutable data can safely be shared.

Adaptive heap pressure control

LazyRAM monitors Java heap usage while Minecraft is running.

When memory pressure becomes high, rebuildable internal optimization caches can be automatically discarded instead of being allowed to grow indefinitely.

The mod also includes a leak-growth sentinel which watches the heap baseline and retires temporary caches when sustained memory growth is detected.

At critical heap pressure, LazyRAM can request an explicit garbage collection cycle.

These systems are automatic and configurable.

Deep AFK mode

LazyRAM includes an automatic Deep AFK mode.

By default, after 60 seconds without keyboard or mouse activity, LazyRAM can:

• Retire temporary optimization caches.
• Clear cached model/predicate lookup data.
• Remove existing particles.
• Stop processing and spawning new particles while AFK.
• Run a garbage collection cycle.
• Pause the integrated server simulation in singleplayer.

As soon as keyboard or mouse activity is detected, normal operation resumes automatically.

In singleplayer, this means the world simulation can be frozen while you are away and resumed when you return. Multiplayer servers are not paused.

Crash and hang protection

LazyRAM also contains an optional aggressive crash/hang guard.

By default:

• Fatal Minecraft crashes can immediately terminate the JVM instead of opening the normal crash screen.
• A watchdog monitors the client render loop.
• If the client stops responding for approximately **45 seconds**, the watchdog can forcibly terminate the JVM.
• Resource reloads receive an extended grace period to avoid treating heavy reload operations as a hang.

These features can be disabled in the configuration file if you prefer Minecraft's normal crash behaviour.

Configuration

LazyRAM intentionally has no in-game configuration screen.

Configuration is stored in:

config/lazyram.properties\

Individual optimization systems can be enabled or disabled separately, including the heap-pressure engine, leak sentinel, explicit GC, crash guard, hang watchdog and Deep AFK behaviour.

Compatibility

• Minecraft: 1.21.1
  • Mod loader: NeoForge 21.1+
  • Side: Client only
  • Java: 21
  • Server installation: Not required
  • License: MIT

LazyRAM uses Mixins to modify low-level Minecraft client memory structures, so when combining it with other mods that heavily modify the same rendering, model or BlockState internals, testing the combination is recommended.

Philosophy

LazyRAM does not add gameplay content and does not lower visual quality to save memory.

Instead, it focuses on reducing duplicated data, using more compact representations, cleaning temporary lookup structures when they become cold, and reacting automatically to memory pressure.

Install it and let it work in the background.

Thanks to intergrav for cozy badges! (if someone wants to see here is the link https://intergrav.github.io/devins-badges-docs/badges/cozy/)