This is actually a serious problem when using complex data structures that consist primarily of pointers between memory locations (example: linked lists or tree

This is actually a serious problem when using complex data structures that consist primarily of pointers between memory locations (example: linked lists or trees): this is the one case where 64-bit can actually be significantly slower than 32-bit. Imagine a doubly linked list that contains "int" values: on 32-bit each node would be 96 bits, on 64-bit each node would be 160 bits.