FastFurnace--

This mod is a fork of the FastFurnace mod for Minecraft 1.12.2.

Original Mod

This mod tweaks the functionality of the Furnace by registry replacing, improving its TPS performance (not smelting speed!)

Similar to FastWorkbench, it caches the last recipe used, and checks this recipe first before re-scanning the entire registry.  This is significantly faster due to the vanilla furnace scanning the entire furnace registry each tick, which may be fine for vanilla, but in a modded environment, gets very large very quickly.

Any mod utilizing TileEntityFurnace will also receive the benefits of having this mod installed.

External Things

In addition,this mod let furnaces could store smelt XP like in new version.

When a furnace smelts an item, the experience gained from smelting is saved within the furnace.You could get XP stored by taking items from output slot or destorying the furnace directly.