> - Comparing single-threaded performance in a GIL implementation against single-threaded performance in a GIL-less implementation is considered an unfair compa

> - Comparing single-threaded performance in a GIL implementation against single-threaded performance in a GIL-less implementation is considered an unfair comparison. A GIL-less will do extra book-keeping that will necessarily result in slower single-threaded performance. Unless you can choose between having the GIL or not, I think it's perfectly reasonable to compare the performance. If you can choose, then I think it's still useful to know the kind of overhead you're adding.