Realm does not have a concept of faulting like Core Data does. In Core Data every object is essentially a copy of a representation in the underlying data store (usually sqlite), so instantiating the object is quite expensive as all the properties have to be retrieved and copied into the object, and before you have done that it is very limited what you can do with the data.

In Realm the object you see is a direct representation of the underlying data, it does not have to copy in all the properties. When you access them, it is the property directly from the db you are getting, not a copy stored in the object. This means that it takes up a fraction of the memory space, and it also means that queries and similar operations can work on the objects directly in the db, without having to instantiate them in objective-c. This means that you can easily scan over millions of objects, without causing a single "fault".

When manually traversing objects you still have to instantiate them, but since they don't have to copy any data, it is a far more lightweight process than faulting.