This hash is only 64 bits, so if you have more than ~10^9 or ~2^30 elements being hashed, collisions will become an issue. Granted, most people don't have this

This hash is only 64 bits, so if you have more than ~10^9 or ~2^30 elements being hashed, collisions will become an issue. Granted, most people don't have this problem, but it's not nobody.