OptCraft
by imattas
OptCraft is a Fabric client mod that targets frame-rate stability and CPU and memory overhead during ordinary play.
What it does
OptCraft skips duplicate chunk rebuild scheduling where it is safe to do so, reduces repeated allocations in per-tick client logic, and caches repeated client entity lookups to cut redundant work. Identifier objects are canonicalized through an LRU cache, which also trims allocations on the packet path.
Non-critical work such as debounced config saves and resource sampling runs asynchronously. A Maximum Performance Mode turns on and tunes the major optimizations automatically, while a safe mode lets players tune individual modules and enable more aggressive presets. Each performance feature can be toggled independently through a modular system.
Compatibility Mode disables the high and extreme risk patches for maximum mod compatibility. OptCraft runs on the client alone, so servers need nothing, and it needs Cloth Config API, Fabric API and Mod Menu. It is published for Fabric only, across 18 release versions, 1.20.1 – 1.21.11, under All rights reserved; it is not open source.
Key features
Chunk rebuild scheduling
Duplicate chunk rebuild requests are skipped where the change is safe, reducing wasted work during movement.
Per-tick allocation reduction
Repeated allocations in hot per-tick client logic are reduced to lower memory churn.
Entity lookup caching
Repeated client entity lookups are cached, so the same results are not recalculated each frame.
Maximum Performance Mode
One switch enables and tunes the major optimizations automatically, for players who do not want to set each module.
Modular toggles
Each performance module can be switched on or off independently, and a safe mode allows fine tuning of individual modules.
Compatibility
Latest build for each game version and loader.
1.21.x12 of 12 versions with builds
1.20.x6 of 6 versions with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 3
Use cases
Who it’s for: Players on Fabric who want to reduce frame-rate stutter and CPU and memory overhead on their own client. Servers do not need the mod.
How it compares
Xodium is a Fabric client mod for 1.21.11 only and is not open source under All rights reserved. Fluorium is also a Fabric client mod, for 1.21.5, and is open source under the GNU General Public License v3.0 only. Prism Performance is a Fabric client mod covering 1.21 – 1.21.11 under the MIT License, and it is not open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| OptCraft | Fabric | 1.20.1 – 1.21.11 | Client-side only | 2026-03-03 |
| Xodium | Fabric | 1.21.11 | Client-side only | 2026-03-28 |
| Fluorium | Fabric | 1.21.5 | Client-side only | 2025-05-21 |
| Prism Performance | Fabric | 1.21 – 1.21.11 | Client-side only | 2026-03-23 |
Questions
Does OptCraft need Fabric API?
Do servers need OptCraft installed?
Which game versions does OptCraft support?
What does Compatibility Mode change?
In the catalog
OptCraft is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 19,862 mods support Minecraft 1.21.11.
Similar mods
What the author says
OptiCraft is a client-side Fabric performance mod focused on improving FPS stability, lowering stutter, and reducing unnecessary CPU/memory overhead in common gameplay scenarios. It uses a modular optimization system so each performance feature can be toggled independently. You can run it in safe mode, tune…
Official listing
- Modrinth page
- modrinth.com/mod/optcraft_fabric
- Owner
- imattas
- Published
- 2026-03-03
- Updated on Modrinth
- 2026-03-03
- Facts verified
- 2026-10-15