Reset Furnace Burn Time to Vanilla Default
Returning to Normal Speed
If you've changed the burn time modifier and want to restore the original Minecraft smelting speed, set the value back to its default.
Using Mod Menu
Open the pause menu and go to Mod Menu. Find Configurable Furnace Burn Time and locate the burn time modifier setting. Change the value to 1.0, which represents vanilla speed. The change takes effect immediately.
Editing the Config File
If you're editing the config file directly, open it in a text editor and set the burn time modifier to 1.0. Save the file and restart your game.
Verification
Once applied, furnaces will smelt items at the standard Minecraft pace. You can verify this by placing an item in a furnace and observing the smelting progress bar—it should match vanilla behavior.
If you ever want to adjust speed again, simply change the value from 1.0 to your preferred multiplier.