This comment has a pet-peeve of mine, which is using the word "efficient" where it's unclear what the cost and benefit are. Efficiency is just cost per benefit, so it's not a very meaningful word if you don't know what the cost and benefit are.

I don't think you're wrong, I just am not entirely clear on what claim you're making. I'll venture based on context that the cost you're talking about is either electrical charge or time, but it's very unclear what benefit you're talking about.