Comment by WalterGR

“Forth isn't particularly fast either. As an interpreted language, it is blazing fast, but the speed tax of the threaded model still has to be paid, so it will generally be slower than code produced by a C compiler.”

Not being familiar with this sense of “thread,” I found a good explainer here: https://www.complang.tuwien.ac.at/forth/threaded-code.html

And, as always, Wikipedia: https://en.m.wikipedia.org/wiki/Threaded_code