LC²H [Lost Cities: Multithreaded]

Lost Cities generates large cities, and this Forge add-on changes how that work is scheduled. Its generator pipeline runs off the Minecraft main thread through an async scheduler and parallel worker pools, so city generation can proceed in parallel. A thread-safe translation layer isolates state that Lost Cities would otherwise share unsafely, and multi-tier caching reuses results that have already been computed.

The mod is aimed at worlds with heavy city generation, where Lost Cities is the source of most of the load. An optional GPU acceleration path exists, and the in-game configuration screen replaces the old commands. The author states that the mod is compatible with C²ME, and that Sinytra Connector sync and loader edge cases were fixed in version 3.2.0.

The mod is published for Forge only, across six release versions, 1.20.1 – 1.20.6. Client and server both need it, so the server and every player run it. The code is public, but the license is a custom one and the project is not open source.