Lithium is a free, open-source optimization mod for Minecraft that speeds up the game's internal logic, things like physics, mob AI, and block ticking, without changing how vanilla actually plays. It helps both single-player worlds and multiplayer servers, works on Fabric, NeoForge, and Quilt, and doesn't need Fabric API.
Lithium is a performance mod for Minecraft: Java Edition that focuses on the parts of the game you don't see. Instead of touching graphics, it speeds up the game's internal logic: the physics, mob behavior, and world updates the game calculates every tick. It's made by CaffeineMC, the same team behind Sodium, and the two are often installed together.
The key thing to understand about Lithium is what it doesn't do: it doesn't change how the game plays. Redstone, mob spawning, drop rates, farm behavior: all of it stays exactly the same as vanilla. You get the speed-up without any of the side effects that usually come with modifying game mechanics.
Minecraft constantly runs calculations in the background to keep the world moving. Every tick, it updates mob AI, processes block and fluid behavior, handles physics, and works through countless small tasks. A lot of that code isn't written for maximum efficiency. Lithium rewrites many of those systems to do the same work with less effort.
Under the hood it's not one big change but a large set of separate optimizations, most of which don't depend on each other. That design has a practical upside: if one specific optimization ever clashes with another mod, it can be switched off on its own through a config file while everything else keeps running. Most people never touch that file, and they don't need to. Lithium works with no setup out of the box.
The clearest gains show up in tick performance. On a server, lighter ticks mean the hardware can handle more entities, more loaded chunks, and more players before it starts to struggle. Server admins are the audience that benefits most directly here.
Single-player still gains, just less obviously. Even when you're playing alone, Minecraft runs an internal server in the background to tick your world. Lithium optimizes that too, which frees up your processor for other work, and that can translate into smoother frame rates and better responsiveness. It's worth being clear about the mechanism though: Lithium isn't a rendering mod, so any FPS change is a knock-on effect of a lighter CPU load, not the mod drawing frames faster. For rendering improvements, that's Sodium's job.
No. Keeping behavior identical to vanilla is the whole point of the project, and it's a strict rule rather than a nice-to-have. That commitment is why Lithium is officially allowed in Minecraft speedrunning, a community that bans anything giving an unfair advantage or altering how the game runs. If a mod is trusted there, you can be confident it isn't quietly bending the rules.
Lithium runs on both sides, and it doesn't need to be on both at once. That flexibility catches some people off guard, so here's how it breaks down:
Because a server-side install doesn't require anything from players, admins can add Lithium without asking everyone to change their setup.
Lithium and Sodium are the classic pairing. They work on completely different layers (Sodium handles rendering on the client, Lithium handles game logic), so they don't overlap or conflict. Running both is one of the most common ways to get a well-rounded performance setup, and CaffeineMC designed them to sit side by side.
Compatibility with the wider mod scene is a priority too. Lithium is built to leave gameplay untouched, which keeps it out of the way of most other mods. In the rare case something does clash, the per-optimization toggles give you a way to disable just the part causing trouble.
Lithium runs on Fabric, NeoForge, and Quilt. Fabric and NeoForge each get their own builds every release; Quilt runs on the Fabric-compatible build. You'll want the download that matches both your Minecraft version and your loader.
CaffeineMC sorts version support into tiers, and it helps to know which one your version falls under before you install:
The short version: if you're on a current release like 26.2, you're on the actively developed branch. Older builds remain available for a wide range of past versions, with 1.21.1 and 1.20.1 kept around as long-term support. Support tiers do shift over time, so it's worth checking the official project page for your exact version.
No. Lithium runs on its own and doesn't require Fabric API, which sets it apart from a lot of Fabric mods. You just need the mod loader itself (Fabric Loader or NeoForge) and the Lithium file in your mods folder. If you're running other mods alongside it, some of those may still need Fabric API for their own reasons, but that's on them, not Lithium.
Before downloading, sort out two details: your Minecraft version and your loader. Lithium ships separate files for each Minecraft version, and separate builds for Fabric and NeoForge, so the file has to match both. Grab the wrong version and the game will refuse to load it.
Lithium is published on the official CaffeineMC project pages (Modrinth and CurseForge) as well as GitHub. Pick the build tagged for your Minecraft version, and choose Fabric or NeoForge to match your setup. If you're on Quilt, use the Fabric-compatible build. New to this? Our guide to installing Minecraft mods covers the basics.
Installing Lithium is about as simple as mods get: no dependencies, no config, no new world required. It comes down to having the right loader and dropping one file in place. The steps differ slightly depending on whether you're on Fabric or NeoForge.
mods folder (%appdata%\.minecraft\mods on Windows, ~/Library/Application Support/minecraft/mods on macOS, ~/.minecraft/mods on Linux)..jar into the mods folder..jar into your mods folder.Quilt doesn't have its own dedicated Lithium file. If you're running the Quilt loader, use the Fabric build of Lithium for your Minecraft version and install it the same way you would on Fabric.
For a dedicated server, put the correct Lithium build in the server's mods folder, using the loader your server runs (Fabric or NeoForge), and restart. Players joining the server don't need to install anything on their end.
Lithium doesn't add a menu or any visible interface, so there's nothing obvious to look for in-game. The most reliable check is your mod list: add the Mod Menu mod on Fabric to see Lithium listed, or check the server console/log on startup, where loaded mods are recorded. If the game launches normally with the file in your mods folder and no crash, it's running.
If you cannot tell which mod is involved, our guide to mods that are not working covers narrowing a conflict down.
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It optimizes the game's internal logic, physics, mob AI, block ticking, and the world-ticking the game does every tick, so the same work costs less performance. It doesn't change how anything plays; it just makes the existing systems run more efficiently.
It can, but indirectly. Lithium optimizes game logic rather than rendering, so it lightens the load on your CPU, which may improve frame rates and responsiveness. For direct rendering gains, pair it with Sodium. There's no official fixed FPS figure, since the benefit depends on your hardware and what's happening in your world.
Yes, and it's the standard combination. Sodium handles rendering on the client while Lithium handles game logic, so they cover different areas and don't conflict. Both come from CaffeineMC and are meant to run together.
Yes. Lithium is well suited to servers, lighter tick times let the hardware support more entities, chunks, and players. Install it in the server's mods folder using the server's loader.
No. Lithium works on either side independently. A server-side install improves the server without players needing the mod, and a client-side install helps your own game. It never has to be on both at once.
No. Lithium runs without Fabric API. You only need the loader (Fabric Loader or NeoForge) and the Lithium file itself.
As far as any mod is, yes. It is open source, it comes from CaffeineMC, and it deliberately makes no gameplay changes, which is why it is permitted in Minecraft speedrunning where anything altering how the game runs is banned. Back up worlds you care about before adding mods, as you would with any of them.
Sodium is a client-side optimization mod for Minecraft that replaces the game's rendering engine with a faster, modern one. It significantly improves frame rates and reduces micro-stutter without changing how the game looks or plays, and it stays compatible with a wide range of other mods.
ModernFix is an all-in-one optimization mod for modded Minecraft that speeds up the launch process, lowers memory use and backports a long list of bugfixes. It does not touch rendering, so it sits alongside Sodium, Lithium and FerriteCore rather than replacing any of them, and it matters most on large modpacks.
FerriteCore is a memory optimization mod for Minecraft: Java Edition. It rewrites some of the game's most heavily duplicated internal data structures so a modded instance holds the same world in less memory, which can reduce garbage-collection stutter on setups that were running short. It runs on Fabric and NeoForge, on the client and the server, and needs no other mods.