Celeris

Celeris is a performance library for NeoForge mods. It gives other mods fast building blocks so they can do heavy work without slowing the game down. On its own it adds nothing you can see in game: you install it because a mod you want needs it.

🎮 Mods that use it

⚡ What it gives those mods

• 🧵 Work off the main thread. Mods hand heavy jobs to worker threads and get the results back on the game thread through lock-free queues, without stalling a tick or a frame.
• 🧠 Less garbage-collector pressure. Large buffers live in off-heap memory, so big data does not cause GC pauses.
• 📐 Vector math. Bulk number crunching uses the CPU's SIMD units when Java allows it, with identical results when it does not.
• 🗜️ Compression. Native zstd for mods' own data (no JVM flags needed), and deflate for network packets.
• 🏃 Batch physics. Thousands of entities moved in one pass, following vanilla's movement rules exactly (Velox uses it for dropped items).

🛡️ Safe everywhere

• ✅ Every fast path has a pure-Java fallback. If something can't run the fast way on your machine, Celeris uses the slower one instead of crashing.
• ✅ Optional on both sides of a connection: players without Celeris can join a server that has it, and you can join any server with it.
• ✅ Network payloads are size-capped and malformed packets are dropped.

📦 Requirements

• 🟩 Minecraft: 1.21 – 1.21.11 and 26.1 – 26.3. Download the file made for your version.
• 🔶 Loader: NeoForge, on the client and on the server.
• ☕ Java: 21 for 1.21.x, 25 for 26.x.

🔧 Native code

Celeris ships two kinds of native libraries, both built from public source by GitHub Actions on each platform's own runner, from the same tagged commit as every file published here:

• zstd 1.5.7 (Meta's Zstandard, BSD-3-Clause), compiled from the official release tarball (zstd-1.5.7.tar.gz, SHA-256 eb33e51f…6fa3, checked by the build), plus a few small functions of Celeris's own that let Java 21 call it without extra flags: native/zstd.
• The physics kernel, Celeris's own C++ code: native/.

The release workflow builds them, packs the jars and uploads them here; GitHub releases also carry a Java-only file with no native code at all.

📚 Learn more

Speed tips, how it works, the full version list and the guide for mod authors are on GitHub.

Code: AGPL-3.0 · Art: CC BY-NC-SA 4.0 · Made by Panzer