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How to optimize Minecraft mods?

Minecraft, the sandbox game that has captured the hearts of millions, is not without its technical hiccups, especially when it comes to the Java Edition. Players often find themselves turning to mods to enhance their gameplay experience, seeking improvements in performance that the Vanilla version doesn’t quite deliver. But what happens when the mods themselves become a part of the problem?

The world of Minecraft modding is vast and varied, with a plethora of options available to the avid gamer. Mods like Sodium and Optifine have been game-changers, offering significant performance boosts by optimizing rendering engines and math functions. However, the modding scene is not just about the big names; it’s also about the countless smaller mods that contribute to the game’s customization.

The issue at hand is not the lack of mods but rather the way they are packaged. Many mods, even popular ones, suffer from inefficient packaging, with resources such as textures, models, shaders, recipes, tags, and achievements not being stored optimally. This leads to unnecessary bloat and can significantly impact the game’s performance on players’ systems.

Minecraft mods in detail

Minecraft mods, which are essentially Java Archive (JAR) files, are a way for players to enhance and personalize their gaming experience. These mods can range from simple additions that tweak gameplay to complex new systems that transform the game entirely.

Firstly, mod developers write the code for the mod in Java, the same programming language that Minecraft is written in. This code modifies or adds to the existing Minecraft code to change the game’s functionality. Once the mod is written and tested, the code is compiled into a JAR file. This is a compressed package containing all of the necessary files, such as class files, metadata, and resources like textures or language files.

The JAR file is the final product that players download and install. To ensure compatibility and easy management, mods are often designed to be compatible with Minecraft mod loaders like Forge or Fabric. These mod loaders act as intermediaries between the mod and the game, helping to manage and load the mods without the player having to modify the game’s core files.

For distribution, mod creators usually upload their JAR files to modding community websites like CurseForge or Modrinth, where players can safely download and install them. Some mod packs are collections of mods that have been put together and configured to work together, often centered around a general theme like tech, quests, or magic. These packs can be installed using custom launchers or installers that simplify the process.

The big problem

Resources in Minecraft mods include everything from textures and models to language files and sound clips. These are the elements that bring a mod to life, providing the visual and auditory enhancements that make gameplay more engaging. However, these resources, particularly image files like PNGs, can be deceptively complex.

PNG files are indeed compressed, but compression doesn’t equate to optimization. Many PNGs carry additional metadata that, while useful in some contexts, are redundant for Minecraft’s purposes. This metadata can bloat the file size unnecessarily, leading to larger mod files and, by extension, longer loading times and increased memory usage.

Optimizing these PNG files involves stripping away this excess metadata and ensuring the image is compressed efficiently without losing quality. This process not only reduces the file size but also streamlines the mod, making it leaner and more efficient.

This is one of the biggest problems, but not the only one. I want to tell you that the most used file format by Minecraft is JSON. Yes! The JSON files also require some optimization.

The JSON files

JSON’s simplicity and ease of use make it an ideal format for storing data. However, the manual creation of these files by mod developers can sometimes lead to inconsistencies and errors. The lack of a standardized method for processing and validating these files means that invalid characters can slip through, potentially causing issues during gameplay. Fortunately, Minecraft’s robust design often allows the game to ignore such discrepancies without affecting performance.

The challenge for the modding community is to maintain the integrity of these files while fostering the creativity that modding brings to the game. Some solutions could include the development of specialized tools for validating JSON files or community-driven standards for creating error-free data. Such measures would not only streamline the modding process but also enhance the overall gaming experience.

There is a tool

Minecraft enthusiasts and mod developers, rejoice! I made a tool that promises to enhance your gaming experience by optimizing the performance of your Minecraft mods. It’s called MC-Repack, and it’s a simple command-line utility designed to create optimized and repacked copies of .jar files, which are essential for Minecraft mods.

MC-Repack works by minifying JSON files, optimizing PNG files, and removing unnecessary files that may have been mistakenly included in mods, such as project files from Blender or Photoshop. This not only reduces the size of the mods but also improves their loading speed, making your Minecraft adventures smoother and more enjoyable.

One of the key features of MC-Repack is its ability to optimize files without compromising quality. For example, it checks the sizes of JSON and PNG files when compressed and uncompressed, choosing the smaller one, ensuring that the optimization process retains the integrity of the mods while enhancing performance.

MC-Repack is not just for players; it’s also a valuable tool for mod developers and resource pack makers. By providing mods with smaller file sizes and optimized assets, they can offer a better experience to their users. Plus, MC-Repack displays any errors that occur during the repacking process, allowing for quick troubleshooting and ensuring a smooth operation.


Installation of MC-Repack is straightforward. Users can download the latest version from the Releases page on GitHub or install it using Cargo, a package manager for Rust.

1. From downloads page

Check the download page for the latest version of MC-Repack.

2. Using Cargo

If you have Rust installed (this includes Cargo) then use the following command:

cargo install mc-repack


Once installed, MC-Repack can be used by simply typing a command in the shell or terminal, specifying the file or directory to be optimized.

You simply provide the path to the Minecraft mod or resource pack you want to optimize as an argument:

mc-repack <file|directory>

<file|directory> can be the path to a single mod file (e.g., .jar) or a directory containing the resource pack.

If you want to develop a tool that uses MC-Repack, there is a library called mc-repack-core available. Check its page or its documentation.

Can it be better?

I have a vision to develop this tool even further, and I’m calling on the community to spread the word. By sharing information about MC-Repack, more Minecraft players can discover its benefits, leading to a larger user base and potentially more feedback that can be used to improve the tool.

So, if you’re a fan of Minecraft and love to mod your game, give MC-Repack a try. And if you find it as useful as many others have, don’t hesitate to share it with your fellow gamers. After all, the more people use and support tools like MC-Repack, the more they can evolve to meet the needs of the community. Happy gaming!

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