Right. If the spec is being used then all the patches will be applied and the configure options specified in the spec will be used (duh
). I don't believe there are many default CFLAGS options set (I think just -O2), so he might want to optimize those anyway.
I am not sure if there are any additional CFLAGS set when the original RPM is built, but I imagine they really can't add much or it would break compatibility.
Either way, I'd recommend tweaking the spec before compiling, or not using it at all and doing it all from clean source. I've always just done the latter and haven't had any problems.
Then again, what do I know?