How to boost FPS in Minecraft 1.21.1 on Fabric

Low FPS in Minecraft 1.21.1 usually comes from a few causes you can fix: view distance, memory, background apps and missing optimisation mods. Work through the list below, changing one thing at a time so you can see what helped.

1. Measure first#

Turn on the FPS element on your FireClient HUD and play the same world for a few minutes before you change anything. Write the number down. Without a baseline you cannot tell what worked.

2. Lower the distance settings#

Render distance and simulation distance have the biggest effect on most PCs. Try 10 to 12 chunks for render distance, and 6 to 8 for simulation distance, then raise them if you have headroom. Fancy graphics, smooth lighting and high particle settings cost frames too.

3. Set sensible memory#

More RAM is not always faster. For Fabric with performance mods, around 4 GB is a comfortable start. Our RAM guide explains how to pick a number and where to set it in the launcher.

4. Use Java 21#

Minecraft 1.21.1 runs on Java 21. An old Java runtime can cause slower performance or refuse to start the game at all.

5. Add performance mods from Modrinth#

Fabric has well-known optimisation mods on Modrinth, including Sodium for rendering, Lithium for game logic and FerriteCore for memory use. Always open the mod page and check that it lists Minecraft 1.21.1 and Fabric before you install it. The FireClient launcher has a mod manager with Modrinth support and a curated Performance pack. The mods guide shows the steps.

6. Close what you do not need#

Browsers with many tabs, screen recorders and overlays compete for memory and GPU time. Close them while you test, and make sure your laptop is plugged in and not on a battery saver plan.

7. Compare and keep what works#

Check your FPS number again after each change. If something made no difference or caused crashes, undo it. Results depend heavily on your CPU, GPU and the mods you run, so treat the numbers here as a starting point, not a promise.