There's a talk by a Nvidia scientist I just saw where he talks about compute efficiency in terms of flops/joule and explicitly mentions vectorized instructions as one of the energy savers. I'll see if I can find it.

Edit: found it (I think) I can't remember where in the presentation but he does mention energy efficiency as a proxy for performance. https://m.youtube.com/watch?v=kLiwvnr4L80

Edit 2: about 26:40 he starts talking about energy use in the context of performance.