Percentages are for suckers. If you're not optimizing your code with actual use cases then you're just wasting your time. Id say 90 percent of code any one would ever write would not provide any benefit if it "ran faster".

No one will ever know or care that a 5ms operation only takes 2ms because of how "savvy" you are. No one knows or cares what language you used. Its just a program.

If you can produce a working program in a high level language but chose to use a low level one.... whyy?