recent mingw -O3

[jbk]

I have found that for certain type of programs option -O3 can give a big performance boost, specifically my experimental decimal math routines due to it's inherent inefficiency can gain almost 100% speed boost when choosing -O3 coupled with the option -march=native over that of -O2
in my shift routines I intentionally chose to use literal constants so that gcc or g++ could optimize division or modulus with magic numbers