FermiumMixins
by fonnymunkey
With FermiumMixins installed, Forge players get over 170 tweaks and patches to vanilla Minecraft and several mods, and each can be switched off in the config.
What it does
FermiumMixins is a general purpose mixin tweaker for Minecraft 1.12.2. Its patches change vanilla behavior in many places, and the mod lists the patches it currently applies. Its focus is performance improvements and bug fixes, and each individual tweak can be toggled in the FermiumMixins config file. Mod compatibility warnings are included, and the default config options are disabled, so a fresh install changes nothing until a tweak is turned on.
The mod requires FermiumBooter, which must be present alongside it on Forge 1.12.2. Client and server both need the mod, so the server and every player run it. The author's sister mod RLMixins concentrates on patches for the RLCraft modpack, and both can be used at the same time. Source code and the issue tracker are public, and the author takes bug reports on GitHub. The license is All rights reserved, so the code is not open source.
Key features
Over 170 tweaks
The mod bundles more than 170 patches that change vanilla and several mods, ranging from new behavior to fixes.
Single-tweak toggles
Each tweak can be turned on or off separately in the config, so a server can keep only the patches it needs.
Compatibility warnings
The config includes warnings for known mod conflicts, shown so players can decide which tweaks to disable.
Disabled by default
Every option starts off, which keeps the mod out of the way until an owner chooses which patches to apply.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Server performance tuning
Server owners can enable selected performance patches and leave the rest disabled to test their effect on a modded world.
Modpack patching
Pack makers can combine FermiumMixins with RLMixins to cover fixes in a RLCraft modpack.
Who it’s for: Modpack authors and server owners running Forge 1.12.2 who want to pick individual vanilla and mod patches and toggle them from one config file.
How it compares
Ender's Modpack Tweaks is an MIT-licensed, open source Forge mod for 1.12.2 that needs the client and server to run it. ThaumPotion Tweaker is a Forge mod for 1.12.2 that is not open source, is released under All rights reserved, and can run on the client or server as optional. Ore Tweaker is open source under the MIT License and covers 1.7.10 – 1.18.2, a wider version range than FermiumMixins.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| FermiumMixins | Forge | 1.12.2 | Client and server | 2026-05-26 |
| Ender's Modpack Tweaks | Forge | 1.12.2 | Client and server | 2025-09-07 |
| ThaumPotion Tweaker | Forge | 1.12.2 | Client or server, optional | 2025-07-26 |
| Ore Tweaker | Forge | 1.7.10 – 1.18.2 | Client and server | 2024-01-04 |
Questions
Does FermiumMixins need FermiumBooter?
Does the server need FermiumMixins?
Can FermiumMixins and RLMixins run together?
In the catalog
FermiumMixins is one of 3,545 Optimization mods on ModsFinder, and one of 1,441 Optimization mods for Forge. 2,920 mods support Minecraft 1.12.2.
More from fonnymunkey
Similar mods
What the author says
FermiumMixins is a general purpose mixin tweaker mod with multiple patches and tweaks to vanilla and various mods. Sister mod of RLMixins ( which focuses on patches for the modpack RLCraft. Both mods can both be used at the same time and are fully compatible.
Official listing
- Modrinth page
- modrinth.com/mod/fermiummixins
- Owner
- fonnymunkey
- Published
- 2025-07-10
- Updated on Modrinth
- 2026-05-26
- Facts verified
- 2026-10-15