I didn't give direct evidence, that's true. You can profile it yourself, but it is the difference between direct access to cached memory (from prefetching) and

I didn't give direct evidence, that's true. You can profile it yourself, but it is the difference between direct access to cached memory (from prefetching) and two comparisons plus two branches then the memory access. To someone who doesn't care about performance having something trivial become multiple times the cost might be acceptable (people use scripting languages for a reason), but if your time is spent looping through large amounts of data, that extra cost is a problem.