That is a fair point, maybe I'm thinking to concretely about it. Was imagining getting a kill-a-watt power meter, and making sure my OS + browser + a website is

That is a fair point, maybe I'm thinking to concretely about it. Was imagining getting a kill-a-watt power meter, and making sure my OS + browser + a website is drawing less than 1W from the wall. What you're saying as a more all-encompassing "efficiency in general" metric makes sense.