c++ - Reasons to not pass simple types by reference?

Question

So far as I understand you should not pass simple types by reference in c++ because it does not improve perfomance, it's even bad for performance(?). At least thats what I managed to gather from the net.

But I can't find out the reason why it's bad for performance, is it because it's quicker for c++ to just create a new simple type than it it is too look up variable or what is it?

Answer 1

If you create a reference, it's:

pointer to memory location -> memory location

If you use a value, it's:

memory location

Since a value has to be copied either way (the reference or the value), passing by reference does not improve performance; one extra lookup has to be made. So it theoretically "worsens" performance, but not by any amount you'll ever notice.