So we all know the main difference between classes and structures:

Classes default as private, structures default as public.

But when it comes down to deciding whether or not to use classes or structures on a basis of performance, this small difference isn't enough.

I would like to know all known differences between classes and structures. I was told by my professor that a structure directly accesses data whereas classes reference their data as a pointer kind of, making structures faster than classes. I don't know I think this is BS, but I want to know what you guys think.

Thanks!