Haven't timed it, but it is fast. You can see how quick the assembly is generated on godbolt [1] And that verifies it is fully compile-time indeed :). [1] ht

Haven't timed it, but it is fast. You can see how quick the assembly is generated on godbolt [1] And that verifies it is fully compile-time indeed :). [1] https://godbolt.org/g/VHvxhi https://godbolt.org/g/VHvxhi edit: it is about 1 second up to n = 262142, after that the compiler delegates the computation to runtime.