After seeing this a couple years ago I started to be more responsible for my PHP code, writing it even with the slightest micro-optimizations possible, since more times people use my code (especially due to nature of PHP being executed in every http request), more energicity they waste because of my lazyness and more they pollute the planet. JIT was NOT included in this experiment, so the number can be much more lower.
I hope you will be responsible for your code so on too (generally I mean people using interpreted languages).
But the paper is right there in the post
https://states.github.io/files/j2.pdf
Maybe i was blind, haven't seen it. Thx, I look into it because i'm curious, but it's long, so need first some time for it