Pulsar Lighting Engine
by pepe_yu
Pulsar Lighting Engine is a Forge optimization mod that replaces the lighting calculation of Cleanroom 1.12.2 with an asynchronous engine.
What it does
Pulsar reimplements Starlight-style lighting algorithms on top of CleanroomLoader, a 1.12.2 runtime, and runs the lighting calculations on separate threads so they do not block the main game loop. Light updates run on the server, and the engine keeps the block-light and sky-light values Vanilla stores in step, so a world already in use is left intact. Its performance values measure main-thread MSPT, with async worker CPU time counted separately.
Because Cleanroom is required, the mod is installed through that loader stack. Pulsar is licensed under the GNU Lesser General Public License v3.0 only and is open source, with public source code and an issue tracker. Files are published as beta builds for Forge, with the latest being 0.5.1 for 1.12.2, released on 2026-10-15.
Installation needs the client and the server to run the same build, since the environment is client and server. Players on a server that runs Pulsar must also have it. Rendering mods like Celeritas, Actinium and Nothirium are listed as working alongside it, according to the page's notes.
Key features
Asynchronous light propagation
Light updates run on separate threads on the server, so the main game loop spends less time waiting on lighting.
Batched block changes
Large groups of block changes are batched together, instead of each change triggering its own separate lighting pass.
Cached chunk light data
Light data is cached in each chunk's NBT, which avoids full relights when nothing has changed.
Synchronized light data
Vanilla's block-light and sky-light data stay consistent with the engine, so existing worlds are kept intact.
Natural lighting for Thaumcraft crystals
Light from Thaumcraft crystals is calculated naturally, and several lighting bugs and quality-of-life fixes are included.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
How it compares
Starlight (Forge) is the closest match: it is also a Forge lighting engine built on Starlight algorithms, is client or server optional, open source under the GNU Lesser General Public License v3.0 only, and covers 1.17.1 – 1.20.2, so it does not target 1.12.2. Dark Redstone is a Forge mod for 1.12.2 that is client and server and under the MIT License, but it is a redstone mod rather than a lighting engine.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Pulsar Lighting Engine | Forge | 1.12.2 | Client and server | 2026-10-12 |
| Starlight (Forge) | Forge | 1.17.1 – 1.20.2 | Client or server, optional | 2023-10-27 |
| Dark Redstone | Forge | 1.12.2 | Client and server | 2023-01-23 |
Questions
Does Pulsar Lighting Engine work on standard Forge?
Does the server need Pulsar Lighting Engine?
Which Minecraft version does Pulsar support?
In the catalog
Pulsar Lighting Engine 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.
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What the author says
This is a mod exclusively for Cleanroom. It requires Java 25 and Cleanroom 0.6.10 or later. Pulsar is an asynchronous lighting engine built for Cleanroom. It reimplements Starlight-style algorithms for Cleanroom and runs lighting calculations on separate threads.
Official listing
- Modrinth page
- modrinth.com/mod/pulsar-lighting-engine
- Owner
- pepe_yu
- Published
- 2026-08-05
- Updated on Modrinth
- 2026-10-12
- Facts verified
- 2026-10-15