Sodium

Sodium is a mod that speeds up rendering of the game on the player's computer. It doesn't add anything new to the game — it just rewrites how Minecraft draws the world, and does so significantly more efficiently. On an average computer, the frame rate increases and the game is smoother especially where there are lots of blocks, water or vines.

It is one of the most widely used mods ever (over 200 million downloads) and it's the first thing more experienced players on a modded server deal with. The reason is simple: without it, modern Minecraft is slow on a weaker computer, even if the server runs well.

What's important is where the mod belongs. Sodium is a client-side mod — the player installs it on their own computer and the server doesn't know about it at all. You as a server operator have nothing to do with it and players have to install it themselves. Conversely, a player with Sodium sees your server the same as without it; only the smoothness on their side differs.

Sodium replaces the original rendering, so it doesn't get along with OptiFine and with mods that interfere with rendering in the old way. When a player sees strange textures or the game crashes, this is the most common cause. Sodium itself can't do shaders (effects) — Iris is added for those.

It pays off to recommend Sodium to players on the website or on Discord. It's free, open source, and for many it's the difference between a playable and unplayable game.

1. Sodium is a client-side mod — it is installed on the player's computer, not on the server.
2. Install Fabric Loader (or NeoForge) for your Minecraft version. Without a loader, mods don't work.
3. Download Sodium from modrinth.com/mod/sodium and select the version exactly for your game version and loader.
4. Open the mods folder: on Windows, enter %appdata%\.minecraft\mods in the address bar (for a profile with a custom location, find the path in the launcher).
5. Place the downloaded .jar into the mods folder. Nothing is unpacked or installed — the file is enough.
6. Launch the game using the profile with Fabric (not the vanilla profile).
7. Check that the mod is running: Sodium options are visible in the video settings and it is listed in the mods list (Mods).
8. Go through the Sodium settings and try what suits your computer — especially water, cloud, and shadow quality.
9. Compare performance before and after (frames per second). The difference is most noticeable in large bases.
10. If you want shaders, also install Iris alongside Sodium — they won't find each other on their own.
11. If the game crashes after installation or textures are broken, the most common cause is OptiFine or another rendering mod — try temporarily removing them.

Sodium is a client-side mod: don't deal with it on the server, just tell players to use it. It has no effect on your server settings.
It doesn't get along with OptiFine or with mods that interfere with rendering. When a player reports broken textures, try removing OptiFine first.
The version must match exactly the game version and the loader. When changing the game version, the mod needs to be replaced with a new version.
Sodium can't do shaders by itself — for those, use Iris Shaders (it works with it).
On a weaker computer, the difference is most noticeable; on a powerful one, it's almost unnoticeable. It's worth telling players in advance so they don't expect miracles.
The mod is free and open source, but it isn't in the official launcher — players have to download it from Modrinth. Don't copy it to other websites; scam bundles appear around mods.