What irks me about this question is that it is almost utterly unrelated to any type of development task, save one: pipelining a repeated math equation in a long

What irks me about this question is that it is almost utterly unrelated to any type of development task, save one: pipelining a repeated math equation in a long loop. And even then, I would bet the time it takes to swap two registers (or even L1 cache) using a third would far outperform the three operations needed because of the fact that they are sequential in nature (ie: they cannot be performed simultaneously by even an advanced CPU). In nearly 30 years of diverse coding experience, I've never once encountered a situation where this solution would be useful.