FastFurnace [FABRIC]

Vanilla furnaces scan the whole furnace registry on every tick, which slows the game down as the number of furnaces and recipes grows. FastFurnace changes that scan through mixins applied to furnace, blast furnace and smoker logic: it remembers the last recipe used and checks that recipe first before scanning again. The author reports the largest gains in modded environments, where the registry grows quickly and modpacks can contain upwards of 700 recipes.

The author ran a test with 9 furnaces smelting cobblestone over the same period, comparing vanilla against FastFurnace, and reports that the number of invocations stayed roughly the same, so the difference comes from the faster checks. The test covered only 70 furnace recipes, so results in larger packs may differ. The mod is an unofficial port of the same idea found in FastWorkbench, adapted to the furnace classes.

The mod is client-side only, so the server and other players do not need it. Only the Fabric loader is supported, with files for 1.21.1, 1.21.4, 1.21.5, 1.21.6, 1.21.7, 1.21.8, 1.21.9, 1.21.10 and 1.21.11. It is released under the MIT License and is not open source.