Reference and Pointer Performance

In most cases, there is no significant performance difference between using references and pointers. Both references and pointers are essentially just storing memory addresses.

However, there can be some minor differences:

1. References may be easier for the compiler to optimize because they cannot be null and cannot be reassigned. The compiler can make assumptions that it can't make with pointers.
2. Pointers may be slightly faster when it comes to polymorphic behavior and virtual functions, because the compiler can avoid an extra indirection.

But in general, the performance difference is negligible and should not be a major factor in deciding whether to use references or pointers. The choice should be based on the semantics and the requirements of your code.

For example, if a function should not modify its argument and the argument will never be null, a reference to const is a good choice:

1void PrintVector(const Vector& v) {
2  std::cout << "Vector: (" << v.x << ", "
3    << v.y << ", " << v.z << ")\n";
4}

But if the function needs to modify its argument or the argument could be null, a pointer would be more appropriate:

1void ScaleVector(Vector* v, float scale) {
2  if (v) {
3    v->x *= scale;
4    v->y *= scale;
5    v->z *= scale;
6  }
7}