A cast iron Dutch oven has been a popular product in the kitchen for decades. Cast iron is an excellent heat conductor, and very durable in use. It takes a while for a cast iron Dutch oven to heat up, but once the pan is hot, it retains the heat well. Because of that, cooking in a cast iron frying pan will save you energy as the heat is distributed very evenly. Cast iron is a sturdy and stable material, but it's also relatively heavy.