Alfheim
by Desoroxxx
Alfheim replaces the vanilla lighting engine with its own implementation, aimed at faster frames and a set of lighting bugs that Alfheim also fixes, for Forge 1.12.2.
What it does
Alfheim is a fork of Hesperus, which itself descends from an earlier lighting mod, and its author describes it as a continuation rather than a patch set, because the internal changes go well beyond fixing bugs. The work includes optimizations of many sizes over both predecessors and a slightly lower overall memory use.
Client performance is a stated focus. Alfheim cuts the number of lighting block updates sharply, caps how many lighting updates run each frame, and avoids forcing lights to update before every frame, which its predecessors do. Alfheim requires MixinBooter and Red Core, and it runs on Forge for 1.12.2 as a client or server mod that is optional on either side.
Alfheim is open source under the MIT License, and the source code and issue tracker are public. Latest file is 1.6 for 1.12.2, published 2025-06-23, after a first release on 2023-09-06.
Key features
Lighting engine replacement
Replaces the vanilla lighting calculation with a reimplemented engine built on the lineage of earlier lighting mods.
Reduced lighting updates
Cuts lighting work sharply and limits how many lighting updates run in each frame.
Extra vanilla lighting fixes
Fixes MC-92, MC-50734, MC-80966, MC-95515, MC-104532 and MC-249343, on top of the fixes from its predecessors.
Predecessor bug fixes
Carries over fixes for MC-3329, MC-102162, MC-116690, MC-117067 and MC-117094 from earlier lighting mods.
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
Phosphor Crash Fix is a Forge mod for 1.12.2 that runs server-side only, under a custom license, and is not open source. Starlight (Forge) is open source under the GNU Lesser General Public License v3.0 only, for 1.17.1 – 1.20.2, and works on either side, and neither needs it. Dark Redstone is open source under the MIT License for 1.12.2 and must be installed on both client and server.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Alfheim | Forge | 1.12.2 | Client or server, optional | 2025-06-23 |
| Phosphor Crash Fix | Forge | 1.12.2 | Server-side only | 2024-01-12 |
| 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 Alfheim need MixinBooter and Red Core?
Does Alfheim have to be installed on the server?
Which Alfheim version supports 1.12.2?
In the catalog
Alfheim 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 Desoroxxx
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What the author says
Alfheim is a fork (or a rewrite depending on your views on the ship of theseus) of [Hesperus] which is a fork of [Phosphor] Alfheim aims to be compatible in all scenarios, and if for any reasons a something is fundamentally incompatible, a warning will tell you what is happening instead of crashing with hardly any…
Official listing
- Modrinth page
- modrinth.com/mod/alfheim-lighting-engine
- Owner
- Desoroxxx
- Published
- 2023-09-06
- Updated on Modrinth
- 2025-06-23
- Facts verified
- 2026-10-15