Yes, I understand. But the only way that gives you good bang for your buck is if you have already exhausted a number of other areas earlier. I.e. it is marginal

Yes, I understand. But the only way that gives you good bang for your buck is if you have already exhausted a number of other areas earlier. I.e. it is marginal gains. How many programmers out there would be better served by spending time learning more about those other areas before they even start thinking about whether the compiler is generating slightly suboptimal assembly?