Performance Mods for a Fabric Server: Lithium, FerriteCore, C2ME and Which Don't Help

Before installing anything: measure

A performance mod fixes a specific problem: game logic, memory, chunk generation or networking. If you don't know which one is yours, installing them blindly is a lottery. spark (it has a mod version for Fabric, Forge and NeoForge) tells you the TPS and what's eating the time of each tick; the spark guide explains how to read it.

Three quick clues: if the lag comes when exploring or flying with elytra, it's chunk generation; if it comes with lots of farms or animals, it's game logic (entities); if RAM is always at the limit with a big modpack, it's memory. Each case has its mod below.

Server-only mods (your friends don't install anything)

These mods work inside the server. Players join with their usual Minecraft or modpack, without adding them.

1. Lithium: first, always

   It optimises game logic (physics, mob AI, block updates, collisions) without changing how Minecraft works: farms and redstone behave the same. It's the one that cuts tick time the most. It runs on Fabric and NeoForge, needs neither Fabric API nor any configuration, and if you ever want to turn off a specific optimisation, it's done in config/lithium.properties.

2. FerriteCore: less RAM

   It reduces the memory the game uses to store blocks and their states. The more mods with new blocks you have, the more you notice it. It runs on Fabric, Forge and NeoForge and has nothing to configure.

3. ModernFix: startup and memory in big modpacks

   It fixes bugs and shortens the startup of heavy modpacks (from several minutes to quite a bit less) and lowers their RAM. On a Fabric server with four mods it barely changes anything; on All the Mods you notice it. It runs on Fabric, Forge and NeoForge.

4. C2ME: generating chunks on every core

   It spreads chunk generation, loading and saving across several processor cores. It's the one that helps most when the lag comes from exploring. Careful: its authors only fully support the latest Minecraft version, and it can clash with mods that change world generation. If something looks off in new chunks, remove it first.

5. ServerCore: Paper's tricks, for Fabric

   It brings Paper-style tweaks: mobs far from players do less work (activation range), a shorter distance of active chunks, and lowering just the view distance or the mob limits when the server is struggling. Out of the box it doesn't change anything in the normal game; you tune it with /servercore settings, and /servercore status shows what's set.

6. Krypton: networking

   It optimises how the server sends data to players, and saves a bit of processor with many people online. With a group of friends you'll hardly notice it. Its authors warn that it's experimental: if you see strange disconnections, remove it.

The ones that DON'T help on the server

Sodium, Iris, Entity Culling, ImmediatelyFast and shaders improve what's drawn on each player's screen: they're client-side. A server has no screen, so they do nothing (and some don't even load). Recommend them to your friends so the game runs smoother for them, but don't put them in the server's mods folder.

The “just add more RAM” trick doesn't work either: spare RAM doesn't raise TPS. If the server isn't running out of memory, the lag comes from the processor, and that's what the mods above fix, not gigabytes. How much you really need is in the RAM guide.

Settings that help as much as a mod

The simulation distance (simulation-distance) says how far farms, redstone and mobs keep working around each player; the view distance (view-distance), how far chunks are sent. Lowering the simulation distance to 6 or 8 is one of the things that helps most, and you barely notice it while playing.

Pre-generating the world with Chunky (it has a mod version too) gets rid of exploring lag in one go: the chunks are already made when someone arrives. It goes really well with C2ME, which speeds up the pre-generation.

How it's done on NapNodes

In the panel, inside your server, “Mods & plugins” → the “Mods” tab searches Modrinth and CurseForge for only what works with your server type and your version, and installs it with its dependencies. If one of these doesn't show up when you search for it, it doesn't have a version for yours yet: don't upload one from another version by hand. If your server is still Paper, switching to Fabric or NeoForge is in “Server type” (with your world inside).

Many modpacks already include FerriteCore or ModernFix. Before installing them, look in “Files”, the mods folder: two copies of the same mod won't start.

Your plan's RAM is yours alone (we don't sell more than there is), so whatever you gain with these mods stays with your server.

1. Make a backup

   In “Backups”, before touching any mods.

2. Install Lithium and FerriteCore

   In “Mods & plugins” → “Mods”, search for them by name and “Install”.

3. Lower the simulation distance

   In “Settings”, “Simulation distance” to 6 or 8.

4. Restart and measure

   With “Restart”. In “Performance” you see memory and processor; with spark, the TPS.

5. Add the rest only if needed

   C2ME if the lag comes from exploring, ModernFix for a big modpack, ServerCore if it's entities. One at a time, restarting in between: if something breaks, you'll know which one it was. They're removed in “Installed” → “Remove”.

Frequently asked questions