Iris VS Indium

Iris Shaders + Sodium - Link - Indium - Link - (Indium is needed for many other Sodium based FPS increasing mods) - Increases performance and shaders performance

You can install iris from here: https://irisshaders.dev/download and they have a complete installation guide here: https://github.com/IrisShaders/Iris/blob/37f491553cea26241a8561da90917c740d7a573c/docs/guide.md

Downloading the latest version off of the official Iris website or GitHub should be safe: https://github.com/IrisShaders/Iris/releases

I did find this on the issue tracker (https://github.com/comp500/Indium/issues/207) Which version of Fabric API are you using? 0.84.0 or newer is required.

Iris Shaders + Sodium - Link - Indium - Link - (Indium is needed for many other Sodium based FPS increasing mods) - Increases performance and shaders performance

Fabric has its own optimization mods. For performance, there is a great Sodium mod. To optimize the Lithium game world. To optimize Phosphor light. These are the main Minecraft optimization mods for Fabric. For shaders there is an Iris mod. Also, if you're playing with Fabric mods, don't forget the Indium rendering mod.

Indium (Required for Sodium compatibility)

You'll need CIT Resewn (and possibly Indium, but I'm not 100% sure). After this, you can follow any tutorial on how to make such resourcepack for OptiFine or MCPatcher, as CIT Resewn supports both.

indium github.com/comp500/Indium and continuity www.curseforge.com/minecraft/mc-mods/continuity allow you to have connected textures with sodium and lithium

If you don't also want Forge mods, they list the combination of Continuity and CIT Resewn as alternatives. (While not directly related to this usecase, if you go that route I would recommend also installing Sodium, Indium, Lithium, and Starlight.)

Indium to make Sodium compatible with some of the following mods.

Since they were Linux computers, then I assume they play Minecraft Java, which means there's a lot of ways to optimize the game to make it run a lot faster, sometimes even 3 times faster. This tutorial fully explains how to download Fabric mods, and this modpack is the best way to optimize Minecraft. The modpack might be a little complicated to download but it's absolutely worth. I downloaded just 2 mods (Sodium and Indium) on a computer that turns into a slideshow when Chrome is opened but they made Minecraft playable. The modpack also allows for shaders that make Minecraft look much better, almost like AAA games with RTX on.