One explanation is that the typical JS output by the TS compiler is more verbose (so more code to load, parse, and run). On the other hand, one can imagine that the TS compiler’s catching classes of errors at compile time means fewer runtime exceptions.

I think the takeaway, however is the theme of a spectrum of energy efficiency, with compiled languages being more efficient than those that are not.

But I still maintain that the overall efficiency of a system is more a function of other factors.