The more CPU-bound your program, the more benefit you'll see from the optimization flags. If your program is constantly waiting around for input on a network ch

The more CPU-bound your program, the more benefit you'll see from the optimization flags. If your program is constantly waiting around for input on a network channel, then it may not help as much. My currently used optimization flags are: -O3 -fno-math-errno -fno-signed-zeros -march=native -flto Only use -march=native if the program is only intended to run on your own machine. It carries out architecture-specific optimizations that make the program non-portable. Also look into profile-guided optimization, where you compile and run your program, automatically generate a statistical report, then recompile using that generated information. It can result in some dramatic speedups. https://ddmler.github.io/compiler/2018/06/29/profile-guided-optimization.html https://ddmler.github.io/compiler/2018/06/29/profile-guided-...