The tag efficiency seems to be pointless. Surely the whole point of Lifehacks is to do things more efficiently. Therefore, the tag could legitimately be applied to every question on the site.
I don't mind deleting it, but I don't think that it could be applied to every question. To me,
efficiency mostly applies to processes with multiple steps that takes time. To make it more efficient, the number of steps can be reduced and/or the ease of performing the steps can increase. I don't think
efficiency applies to this question about balancing a bench grinder on foam to muffle its vibrations.
But as I said, I'm neutral about removing it. The tag is kind of a catch-all whereas other tags would define the scope of a question more clearly.