This seems like a universal-ish mechanism for queueing your recursive function's calls onto a dynamically resizeable stack (placed in the process's heap). This

This seems like a universal-ish mechanism for queueing your recursive function's calls onto a dynamically resizeable stack (placed in the process's heap). This is pretty cool, but I wouldn't say it's "for free", performance-wise, as demonstrated by the performance figures in the article. Although it certainly makes the transformation cheap, implementation-wise.