Lithium

What it does

Lithium rewrites slow parts of Minecraft's game logic: mob AI, block ticking, collisions, chunk handling and more. Everything behaves exactly like vanilla, redstone and farms included, it just takes less CPU. On a busy server that means higher, steadier TPS.

It only needs to be on the server. Players don't have to install it, though it helps singleplayer too.

Install

Install it from the Mods tab for your Minecraft version and loader, then restart. There's nothing to configure.

On Fabric it needs nothing else. Check the Modrinth page for the NeoForge build for your version.

What it pairs well with

• FerriteCore cuts memory use.
• spark shows where the remaining lag comes from.
• Chunky to pre-generate the world, since generating new terrain is the heaviest work of all.

What it won't fix

Lithium makes each piece of work cheaper, but it can't stop a server doing too much of it. Huge mob farms, thousands of item entities, very high simulation distance or exploring fresh terrain still cost a lot. Use spark to find those.

Compatibility

Lithium is careful to match vanilla, so it works with almost everything. If a mod conflicts, Lithium's settings can turn off individual optimisations in config/lithium.properties, and the crash usually names the one involved.