Lithium for Minecraft Java: Download, Install and Fix World Lag

Lithium helps Minecraft Java spend less time processing the world. It optimizes work such as mob behavior, physics and block updates, aiming to preserve the game's normal mechanics. It can help a busy single-player world or a multiplayer server feel more responsive. It does not add blocks, change textures or supply shaders.

Where Lithium fits into a survival world

A base with farms and villagers: the game processes creatures, inventories and block interactions even when you are concentrating on building. Lithium targets parts of that background work. It is worth considering when simulation struggles around an active base, while keeping realistic limits on how much machinery and how many entities you keep loaded.

Single-player progression: your own computer runs both the picture and the world simulation. Install Lithium in the profile where you play; continue using your existing farms, redstone and survival mechanics. There is no new menu routine, tool or activation key.

A shared server: a server owner can install the compatible server build to optimize the simulation for the group. Players do not need to change their client just to receive that server-side benefit. If you only join somebody else’s server, your local installation cannot do that work on the owner’s behalf.

Choose by the symptom: delayed world interactions suggest looking at simulation, choppy camera movement suggests rendering, and delays only on a distant server can involve the connection. Lithium and Sodium address different jobs. Neither makes an unlimited farm free to run; use the defaults and enjoy the same gameplay rather than redesigning machines around an assumed speed increase.

Download Lithium for Java 26.2

Choose one Lithium 0.25.3 file to match the loader used by your Minecraft installation. Both downloads below are original developer files hosted by MineBrush. They are for Minecraft Java 26.2; use neither for Bedrock, mobile Minecraft or a different Java version.

Fabric or Quilt

Lithium 0.25.3 - Fabric and Quilt - Minecraft 26.2 891.46 Kb4 downloads View download

NeoForge

Lithium 0.25.3 - NeoForge - Minecraft 26.2 882.88 Kb3 downloads View download

Do not install both variants together. NeoForge and Forge are different loaders: the NeoForge download is not a Forge build. Lithium itself does not require Fabric API for the Fabric installation, though other mods in your pack may need it.

Will it help the lag you are seeing?

If mobs pause, farms fall behind or blocks take a while to respond in a heavily loaded world, world processing may be the bottleneck. Lithium targets this part of the game. Single-player also runs world simulation internally, so you do not need a dedicated server to benefit.

If the picture becomes choppy when you look across a detailed landscape, rendering may instead be the main problem. Sodium addresses that different workload and can be used alongside a compatible Lithium version. A mod cannot guarantee a particular FPS increase or repair a slow network connection. Installing Lithium on your own computer also cannot optimize somebody else's remote server.

Install it in your own game

1. Back up the world you intend to play, as the developer recommends. Close Minecraft before changing the mod files.
2. Check the launcher's selected instance: it must use Java 26.2 and a matching Fabric, Quilt or NeoForge loader. If you play a managed modpack, use its existing loader and version.
3. Open that instance's game folder. A launcher's folder shortcut is the easiest way to avoid modifying the wrong installation.
4. Put the matching Lithium JAR into the mods folder. Create that folder if needed. Keep the JAR intact; do not extract it or put it in resourcepacks.
5. Remove an older Lithium JAR from the same folder so there is only one installed version. Launch the same modded profile and open your world.

There is no resource-pack activation step and no new world is required. The default settings are intended for normal play. If you inspect the configuration and find an empty file, that is normal: it means no default options have been overridden.

Install it on a server

Stop the server cleanly and back up its world before changing files. Place the matching JAR in the mods folder of a compatible Java 26.2 Fabric, Quilt or NeoForge server, then start that server again. Do not place it in a Bukkit or Paper plugins folder. A vanilla server needs a compatible mod loader before it can load this mod.

Players do not have to install Lithium merely because the server uses it. Conversely, running it on your client does not require a server owner to add it. On rented hosting, use the game instance selected in the host's panel and its file manager, rather than uploading to an unrelated directory.

What changed in 0.25.3?

This release fixes two gameplay problems: a sculk sensor could fail to wake when a player stood on it, and a furnace could fail to wake when its fuel slot was changed through the /item command. These are corrections described in the developer's release notes, not new blocks or extra furnace recipes.

Common problems and practical fixes

• Minecraft reports an incompatible mod: compare the game version and loader with the download label. A 1.21 instance needs its own matching Lithium release, not this Java 26.2 file.
• The game crashes after updating: check for an old second Lithium JAR first. If versions match, temporarily remove the new Lithium file and retry the same instance to see whether the problem follows that change.
• Nothing looks different: that is expected. The mod works on simulation rather than graphics and has no texture-pack toggle.
• A machine or mob behaves unexpectedly: stop using the affected setup until you isolate the conflicting combination. The developer documents individual optimization switches, but most players should start with the default settings rather than copy a random configuration.
• Lag remains: check whether it happens only online, only with shaders, or around a very busy farm. Those symptoms point to different causes; stacking more performance mods is not a reliable diagnosis.

If you need to report a reproducible issue, the developer's issue tracker is the right place. Include the game, loader and mod versions and the relevant crash report, removing private server addresses or account details before posting.

Remove or change versions

Close the game or stop the server, move the Lithium JAR out of mods, then restart. Keep your world backup when changing any modded setup. To update, replace the old JAR with exactly one compatible release; a newer project version does not automatically support an older Minecraft version.

Developer and original sources

Lithium is developed by CaffeineMC and contributors. MineBrush hosts the unmodified release files and provides this player guide. See the official project, the Fabric/Quilt release and the NeoForge release. The project is licensed under LGPL-3.0-only; its corresponding source and configuration documentation are maintained by the developers.