CurseForge · Minecraft mod

Compact Machines Preview Fixer

Fixes the severe memory leak when previewing Compact Machines rooms. Opening a preview can chew through hundreds of MB to multiple GB of RAM that never gets freed, eventually crashing the game. This client side mod cleans that up.

Choose a version Pick your version below, then grab the matching file.

Quick answer

Which Compact Machines Preview Fixer release should I use?

Updated 2 months ago

Latest stable file cmpreviewfixer-21.1-1.1.0.jar

Game version 1.21.1

Loader NeoForge

Compact Machines Preview Fixer cmpreviewfixer-21.1-1.1.0.jar targets 1.21.1 with NeoForge. The project page does not say whether this file belongs on the client, dedicated server, or both. No extra mods listed for this file.

Where it goes

Is Compact Machines Preview Fixer required on the client, server, or both?

The project page does not say whether this file belongs on the client, dedicated server, or both.

Client Source doesn’t say

Dedicated server Source doesn’t say

Loader for this release NeoForge

Required install it here Optional supported, not mandatory Not supported do not install here Source doesn’t say do not assume

The source does not explicitly classify this release as client-only or server-only.

Understand client and server requirements Read the Minecraft installation guide

What else does Compact Machines Preview Fixer cmpreviewfixer-21.1-1.1.0.jar need?

cmpreviewfixer-21.1-1.1.0.jar. Change the file and its required mods may change too.

No extra mods listed for this file

This file does not list any required mods. Do not add a library just because a different file uses it.

This file does not list any required or optional mods.

Before you install it

Add Compact Machines Preview Fixer without breaking your instance.

Built for Compact Machines Preview Fixer cmpreviewfixer-21.1-1.1.0.jar. Pick another file and the loader, install side or required mods may change.

01
Stick to this file

Use cmpreviewfixer-21.1-1.1.0.jar. It targets 1.21.1 with NeoForge; another release may have different loader, side or dependency requirements.
02
Bring the mods it needs

This file does not list any required mods. Do not add a library just because a different file uses it.
03
Put it on the correct side

The project page does not say whether this file belongs on the client, dedicated server, or both.
04
Pick the file you checked

Use the “Get this file” button beside cmpreviewfixer-21.1-1.1.0.jar. It opens that exact file at the source.

About this project

What does Compact Machines Preview Fixer add?

The problem

Right clicking a Compact Machine without a Personal Shrinking Device pops up a little 3D preview of what is inside. Handy! Except every time you open one, the game grabs a huge chunk of memory to draw it, and then never gives that memory back when you close the preview.

Open a few previews of a small machine and your RAM use creeps up. Open a single preview of a big machine (a 45x45x45 room can use a full gigabyte of RAM), and your game can freeze for minutes or crash outright. Open one with a packed Mekanism or Oritech setup inside and you can blow past 50 GB of committed memory in a single click.

Worse, normal heap memory tools show nothing wrong, because the leak is in off heap / GPU memory. Most players just see "Minecraft is eating all my RAM" and have no idea why.

What this mod does

When you open a preview, this mod hooks into the screen and makes sure the memory the preview reserved is properly released as soon as either of the following happens:

You close the preview.
The preview screen swaps in a new preview.

That is it. No new blocks, no new items, no menus, no config. You install it, the leak stops happening.

Symptoms it fixes

Game freezing for several seconds (or minutes) when previewing a large or busy compact machine.
Minecraft's RAM usage climbing every time you open a preview and never going back down.
Out of memory crashes after opening a few previews in a single play session.
Whole PC becoming sluggish because Minecraft has eaten all available memory.

If any of those sound familiar, this mod is for you.

Client side only. The leak is in the preview rendering code, which runs on your computer. You do not need to install this on the server. It will not desync you from other players.

Safe to add to or remove from existing worlds at any time.

Compatibility

Minecraft: 1.21.1
Loader: NeoForge 21.1.55 or newer
Requires: Compact Machines (any 1.21.1 version that still has the broken preview)

If Compact Machines is not installed, this mod does nothing and stays out of the way.

When can I uninstall this?

As soon as Compact Machines itself ships a fix for the underlying preview leak, you can safely remove this mod. Until then, leave it in.

Project description from CurseForge.

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