You can control most of the optimization flags separately, I think most are listed under the various levels here [0], might be interesting to see what causes th

You can control most of the optimization flags separately, I think most are listed under the various levels here [0], might be interesting to see what causes the difference, or if it's one of the unspecified "tuning values". [0] https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html