Effective optimization strategies on modern C++ compilers

Question

I\'m working on scientific code that is very performance-critical. An initial version of the code has been written and tested, and now, with profiler in hand, it\'s time to

Answer 1

Here is something that worked for me once. I can't say that it will work for you. I had code on the lines of

switch(num) {
   case 1: result = f1(param); break;
   case 2: result = f2(param); break;
   //...
}

Then I got a serious performance boost when I changed it to

// init:
funcs[N] = {f1, f2 /*...*/};
// later in the code:
result = (funcs[num])(param);

Perhaps someone here can explain the reason the latter version is better. I suppose it has something to do with the fact that there are no conditional branches there.