I think people often overestimate how smart the compiler is. DJB had a slide deck about this: http://cr.yp.to/talks/2015.04.16/slides-djb-20150416-a4.pdf http:

I think people often overestimate how smart the compiler is. DJB had a slide deck about this: http://cr.yp.to/talks/2015.04.16/slides-djb-20150416-a4.pdf http://cr.yp.to/talks/2015.04.16/slides-djb-20150416-a4.pdf Compilers are really useful... but, if it really has to be fast, you still need to have a human in the loop. I was also under the impression that there hasn't been much improvement in compiling C/C++ in a long time. It would be interesting to compare the performance of gcc from 15 years ago versus gcc today, on a real world piece of code. I suspect you wouldn't see much difference (aside from the changes in C dialect over time), and some added features in the new version. Has anyone run this experiment?