Are any of the shaders energy-efficient, and if no, could a (RAVU) shader be written that is optimized for energy efficiency?

[ahydronous]

What I mean is that, on laptops energy efficiency is often paramount. Obviously using a shader will always use more energy than no shader, but I'm wondering if it is possible to optimize one of the shaders in such a way that you get optimal performance (= quality improvement) per watt.