The cost is on the things mentioned themselves: JIT is not free at all, it may take more CPU power than your actual application during some period! You can act

The cost is on the things mentioned themselves: JIT is not free at all, it may take more CPU power than your actual application during some period! You can actually tell the JVM to not JIT... try that and see just how slow your code runs... it may give you an idea of how much it costs in terms of energy as well if you're able to measure that (I don't know how much that cost would look like, to be honest, I can only imagine it's a significant proportion of the total).