Comparing the energy efficiency of code that's not even doing the same thing is not a useful comparison. If you're running these benchmarks on a server that's a

Comparing the energy efficiency of code that's not even doing the same thing is not a useful comparison. If you're running these benchmarks on a server that's always running full throttle then using more cores will use less power because the software finishes faster. If you're running on a laptop the relationship between core usage, elapsed seconds, and power usage is very non-linear.