How to Optimize Your Fabric Server Performance

Fabric is often the go-to mod loader for players who want to stay close to the vanilla experience while adding lightweight performance and quality-of-life mods. This guide covers the best performance mods for each Fabric version.

💡 Tip: Before installing these mods, make sure you've followed our general Performance Guide for server optimizations that apply to all Minecraft servers.

📝 Note: This guide assumes Fabric is already installed on your server. If not, see our version guide to switch to Fabric. To upload mods, follow our mod installation guide.

Recommended Mods by Version

Different Fabric versions have different mods available. Find your version below for our recommended performance mods.

Mods not listed here either change vanilla behavior or are generally considered unstable by the community.

Fabric 1.21.1 and Beyond

• Lithium: One of the most important mods for performance on a server. Lithium optimizes gameplay logic without changing vanilla mechanics.
• FerriteCore: Moderate reduction in RAM usage from patches to block states and locations.
• ModernFix: Fixes various bugs and improves startup time and memory footprint.
• Krypton: Optimizes the Minecraft network stack to improve connection stability.
• Structure Layout Optimizer: Improves generation speed of structures, especially with larger modded structures.
• Alternate Current: Optimizes redstone dust by reducing unneeded calculations.

Fabric 1.20.1

• Lithium: Optimizes gameplay logic without changing vanilla mechanics.
• FerriteCore: Moderate reduction in RAM usage from patches to block states and locations.
• ModernFix: Fixes various bugs and improves startup time.
• Krypton: Optimizes the Minecraft network stack.
• Structure Layout Optimizer: Improves generation speed of structures, especially with larger modded structures.
• Alternate Current: Optimizes redstone dust by reducing unneeded calculations.

Fabric 1.19.2

This version still has lighting engine issues from 1.18. These mods address the most impactful performance problems.

• Lithium: Optimizes gameplay logic without changing vanilla mechanics.
• Starlight: Greatly speeds up chunk generation and ticking by rewriting the lighting engine.
• ModernFix: Fixes various bugs and improves startup time.
• FerriteCore: Moderate reduction in RAM usage from patches to block states and locations.
• Krypton: Networking and packet delivery optimization.
• Structure Layout Optimizer: Improves generation speed of structures, especially with larger modded structures.
• Alternate Current: Optimizes redstone dust by reducing unneeded calculations.
• Advancements Debug: Rewrites advancement checking to be faster and prevent StackOverflow crashes.

Fabric 1.18.2

This version introduced new world height and terrain generation, creating new performance challenges.

• Lithium: Optimizes gameplay logic without changing vanilla mechanics.
• Starlight: Greatly speeds up chunk generation and ticking.
• ModernFix: Fixes various bugs and improves startup time.
• FerriteCore: Moderate reduction in RAM usage from patches to block states and locations.
• Krypton: Networking and packet delivery optimization.
• Structure Layout Optimizer: Improves generation speed of structures, especially with larger modded structures.
• Alternate Current: Optimizes redstone dust by reducing unneeded calculations.
• Advancements Debug: Rewrites advancement checking to be faster and prevent StackOverflow crashes.

Fabric 1.16.5

This version is generally less performant than newer releases. These mods address the biggest bottlenecks.

• Lithium: Optimizes gameplay logic without changing vanilla mechanics.
• Phosphor: Greatly speeds up chunk generation and ticking (use instead of Starlight on 1.16.5).
• ModernFix: Fixes various bugs and improves startup time.
• FerriteCore: Moderate reduction in RAM usage from patches to block states and locations.
• Krypton: Networking and packet delivery optimization.
• Structure Layout Optimizer: Improves generation speed of structures, especially with larger modded structures.
• Alternate Current: Optimizes redstone dust by reducing unneeded calculations.
• Advancements Debug: Rewrites advancement checking to be faster and prevent StackOverflow crashes.

Next Steps

It is highly recommended to pre-generate chunks on your server. This eliminates terrain generation lag during gameplay.

If you've followed this guide and are still experiencing issues, analyze your server using the Spark profiler. Check out the Spark Guide for instructions on tracking down the specific cause of your lag.

As always, if you get stuck or have any questions, just join our Discord.