Fast Furnace: https://www.curseforge.com/minecraft/mc-mods/fast-furnace-for-fabric

This is similar to fast chests, but for furnaces.

Krypton: https://modrinth.com/mod/krypton

This one optimizes the Minecraft networking stack, using code from the Velocity and Tunity projects.

Duplicates of #41 and #9.

Please search before creating, do one request per issue and fill the missing fields.