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Minecraft 1.21.4 Fabric — Shaders & FPS Optimization

1 minRoute
Routeprism launcher mc 1 21 4 fabric shaders and fps boostminecraft 1.21.4 fabric shaders & fps optimizationhow to set up minecraft 1.21.4 fabric prism launcher

Blueprint for doubling frame rates and installing Complementary or BSL shaderpacks on Minecraft 1.21.4 Fabric using Java 21 (64-bit) and 4096 MiB RAM in Prism Launcher.

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Minecraft & Loader
Minecraft 1.21.4 Fabric
Workflow Task
Shaders & FPS Optimization
Required Java
Java 21 (64-bit)
Recommended RAM
4096 MiB
Loader Stack
Fabric Loader + Fabric API

Blueprint: Minecraft 1.21.4 Fabric × Shaders & FPS Optimization

This route configures **Minecraft 1.21.4 Fabric** inside Prism Launcher for doubling frame rates and installing Complementary or BSL shaderpacks. Start by creating an instance with **Fabric Loader + Fabric API** in the Version tab and assigning **Java 21 (64-bit)** under Java Settings.

Set Maximum Memory (`-Xmx`) to **4096 MiB** so chunk loading, mods, and shaders run without garbage-collection pauses.

Prism Launcher screenshot showing the mod installation user-interface
Mods install straight from Modrinth and CurseForge.

Step-by-step checklist on Windows

  1. Install or update Prism Launcher from /download and click **Add Instance**.
  2. Select the Minecraft version and install **Fabric Loader + Fabric API**, then verify **Java 21 (64-bit)** is selected in Settings → Java.
  3. Use **Edit Instance** → **Mods** → **Download mods** to pull verified jars from Modrinth and CurseForge.

Frequently asked questions

Which Java version do I need for Minecraft 1.21.4 Fabric?

Use **Java 21 (64-bit)** with **4096 MiB** allocated under Edit Instance → Settings → Memory.

Can I export this instance to share with friends?

Yes. Right-click the instance and click **Export** to save a `.mrpack` or Prism ZIP archive.

Get Prism Launcher

Windows, macOS & Linux

Free and open source. Sign in with the Microsoft account that owns Minecraft, then create your first instance.

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Prism Launcher on Windows showing several modpacks and instances