I guess whatever distro uses the least resources.

The power difference is going to be negligible though. Unless you’re running a pentium 4 and all you do is boot the OS, check mail, then shut it down you’d never notice a difference. As soon as you open a web browser any savings goes out the window. The web will destroy any savings a distro has.

Also performant doesn’t necessarily mean more efficient. It could mean it better utilizes the hardware, but because it’s using more of the hardware it’s using more power.