Zefir's Optimizations
by Stikulzon
Zefir's Optimizations moves entity movement for mobs and armor stands onto separate actors so it can run off the main thread on a Fabric server.
What it does
Each mob or armor stand that the mod covers gets its own actor. When an entity's movement is due in a tick, the Async Tick Manager sends the matching actor a message, and the actor handles the request from its mailbox one message at a time. Only basic movement logic for Entity and LivingEntity is moved this way.
Some actions, such as dealing damage or picking up items, must still run on the main thread for safety, so the actor hands those requests back. Gains come from splitting movement work across cores, so a server needs at least two cores to see any difference, and more cores help further. The mod needs Lithium and Scalable Cat's Force to run.
The mod is server-side only: only the server needs it, players join without installing it. Files cover 1.21 and 1.21.1 for Fabric, and the latest is 0.0.1-alpha2 for 1.21.1, an alpha release. The code is published under the Creative Commons Attribution Share Alike 4.0 license and is not open source.
Key features
Movement on actors
Entity movement for mobs and armor stands is handled by Akka actors rather than the main thread.
Mailbox processing
Each entity actor receives movement messages in a mailbox and processes them one at a time.
Main thread handoff
Damage and item pickup stay on the main thread and are passed back from the actor for safety.
Multi-core scaling
Performance gains grow with the number of CPU cores available to the server.
Gallery
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 2
How it compares
Async Pack Scan is a Fabric mod under the MIT License and is open source, for 1.20 – 26.3, but it is client-side only. Async is open source under the GNU General Public License v3.0 or later, works on Fabric, NeoForge and Quilt for 1.21 – 26.3, and is server-side only, so it is closer in environment to this mod. Chlorophyll is server-side only, covers 1.21.4 – 1.21.7 and uses a custom license that is not open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Zefir's Optimizations | Fabric | 1.21 – 1.21.1 | Server-side only | 2024-10-26 |
| Async Pack Scan | Fabric | 1.20 – 26.3 | Client-side only | 2026-09-15 |
| Async | Fabric, NeoForge and Quilt | 1.21 – 26.3 | Server-side only | 2026-10-04 |
| Chlorophyll | Fabric | 1.21.4 – 1.21.7 | Server-side only | 2025-07-11 |
Questions
Does Zefir's Optimizations need Lithium?
Does the server need the mod installed?
Will the mod speed up a single-core server?
In the catalog
Zefir's Optimizations is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 32,366 mods support Minecraft 1.21.1.
More from Stikulzon
Similar mods
What the author says
Zefir's Optimizations is a Fabric mod that adds parallel entity movement using Akka actors. It focuses primarily on separating the movement ticking of mobs and armor stands from the main thread. This can gradually improve the performance on the multi-core server. It works by attaching an actor to each MobEntity and…
Official listing
- Modrinth page
- modrinth.com/mod/zefiroptimizations
- Owner
- Stikulzon
- Published
- 2024-10-20
- Updated on Modrinth
- 2024-10-26
- Facts verified
- 2026-10-15