Tried with a 3.5GB Ubuntu .iso file, results are similar though I also tried b3sum and that was even faster(just 1.8s vs. 19s for sha256sum & 6.7s for md5sum).

Tried with a 3.5GB Ubuntu .iso file, results are similar though I also tried b3sum and that was even faster(just 1.8s vs. 19s for sha256sum & 6.7s for md5sum). So performance is definitely not an argument for md5.