Tested and confirmed : Prior to v1.15, Charcoal used to burn more slowly in the Campfire than the Furnace (6m40s vs 5m20s). Now, it burns for 5m20s in both. A Pine Plank still burns in 3 minutes when used as fuel. Considering the recipe to make charcoal was 10 planks + 6 charcoal = 20 charcoal, or 10 planks = 14 charcoal... Now, the math has changed and its 10 planks + 8 charcoal = 20 charcoal, or 10 planks = 12 charcoal. 10 planks will burn in 30 minutes at campfire (20 minutes in furnace), but 10 planks turned into 12 charcoal will burn for 64 minutes in both campfire and furnace (used to be 14 for 93min at campfire and 75min in furnace). Conclusion : Charcoal is still the best fuel, compared to planks. But it has been nerfed really well. It now takes +33% ressource to turn planks into charcoal, and the burn time has been reduced by 15 to 30%, depending on where you use it. EDIT : I'm wondering if the nerf was intentionnal, or if it's a mistake that burn time is now the same between campfire and furnace. I've already mailed a complaint to Kefir earlier (prior to above math), and I don't want to push my luck. Maybe the community can reach out to Kefir? If it's a bug, it can be fixed.