Modern optimizing compilers are magical. I would need to check assembly but I would actually expect the if to be hoisted out of the loop entirely to relieve pressure on the branch predictor.

It does. I use this port

You need to me careful about benchmarking to find performance problems after the fact. You can get stuck in a local maxima where there is no particular cost center buts it’s all just slow.

If performance specifically is a goal there should probably at least be a theory of how it will be achieved and then that can be refined with benchmarks and profiling.