"It depends". In general, you can regard a reference as the key to a locker. Instead of passing around the things in the locker, you pass around the key. So, references can be used to avoid copying of values, but they are more expensive on overall access. So if you have "large" values, it can be worthwhile to pass them around as references, but Data::Alias might be a better and less convoluted way of avoiding passing around the references.