I'm unconvinced with this article. Whilst obviously a smart guy, I don't think Lemire really works on the same problems most of us do. Looking at his posts and publications it's generally high peformance work on problems that are small in scope. I suspect most people actually work on far bigger projects than he does! Neither do I see from that arctile that he's actually used a modern debugger to its full potential. I rarely step through code in slow motion, but sometimes it's great to see program state. If there are thousands of files in a project I don't know well, I can put breakpoints to test hypotheses about my understanding.