PathWeaver

Mob pathfinding normally runs on the server thread, and a large number of mobs repathing at once can cause tick spikes. PathWeaver runs those searches on spare CPU cores instead, while the main thread keeps going. Each mob still receives its path, and the mod does not change which routes mobs choose, though the project page documents a short list of exceptions.

The author reports that the mean tick time roughly halved with 1024 mobs, and that the worst one percent of ticks dropped 55 to 61 percent. These figures come from the author's own measurements and are linked on the project page, so they are reported here as the author's results rather than independently verified. Gains are expected to be largest on servers where pathfinding is the bottleneck, and smaller where the server slows down for another reason.

PathWeaver is a server required mod, with client optional, so the server must run it and players may leave it out. It requires Fabric API and works with Cloth Config API and Mod Menu when those are installed. Files are published for Fabric only, across four release versions, 26.1.1 – 26.3, under the MIT License, and the code is open source.