> I started by timing how long it took the pans to bring a cup of water to a boil over the maximum gas flame on my stovetop. The copper and the cast iron each took 3 minutes, the aluminum-stainless combination 2.5, and the thin nonstick aluminum just 2 minutes. Light and cheap win for speed.
Not sure that's the right test... speed isn't what you're going for. For example, aluminum foil would very quickly conduct heat straight to the water opposite the flame, rather than distribute it broadly across the surface.
Because heat transfers fastest across the gradient where the temperature difference is greatest, foil would win the day even though it's a terrible cooking surface.
A heavy copper pan would evenly distribute the heat it's given to the sides and all over the bottom rather than straight to the bottom. That's kind of the point.