Let’s use Minecraft as an analogy.
I have a machine (furnace) that contains fuel and food. I need to deplete this fuel every second by 1 and increase the food by 1 until it is fully cooked.
Now multiply this by 100 machines.
What is the best way to do this?
Coroutines?
I would make a timer for your whole game (Minecraft uses ticks). When you first put food in a furnace, store the time it was put in. When the user interacts with the furnace, calculate the “cook level” of the food based upon the time passed (rather than calculating it every frame).
Of course there is a problem with this if you have an animation that runs when something is cooking. In that case, I would change the rate that each furnace checks it’s “cook level”.
Another idea is to limit the amount of furnaces allowed to be spawned.
Yet another idea, is to let two furnaces use only one of their calculations if they started at the same time.