Both. And under the hood, Forth implements a virtual stack machine on top of a non-stack machine, which is inefficient.
I guess I'm just trying to counter all the mythos and happy talk surrounding Forth and stack processing in general. In the end Forth is a highly (too?) simplistic language, a product of its time, and nothing all that special or powerful. It does a lot of stuff poorly and the code tends to write-only. The syntax is so loose that the entire dictionary has to be searched to know you're dealing with a number. It's no mystery that we aren't all coding on it now.