Skyfactory, Agrarian Skies, Skycraft, Skyworld, Skyblock – Melting rock in a crucible using your furnace!

Sure, torches are easy to come by and if you have that mod that allows you to place four of them under a crucible, the speed gain is still negligible. A better idea that produce more heat is a furnace directly under the crucible. If you setup a basic design using hoppers and chests you can have a system that smelts and cooks for you while unattended plus makes lava at the same time and faster than had you used torches!