It depends on what flags are set by the Makefile when you run make. You can override these flags for better optimizations, BUT... it's not recommended. Optimizations CAN break functionality and introduce bugs. If the creator of the code didn't test his code with those optimization flags set, then you can't expect the code to work exactly like you think it should. Your safest bet is to just "./configure && make && make install" rather than trying to set optimizations the code hasn't been tested with.