They don't touch it in this tutorial but typically you don't check just whats in your dictionary. You also use a set of rules to manipulate your dictionary that massively increases the number of hashes to perform. Those 5 million entries quickly passes tens of billions hashes that need to be run. These initial entries might be too short like OP pointed out, but after the rules are applied it might generate many entries that will be long enough to spend time hashing.

The keyspace for WPA is huge and the hash speed is still relatively slow, even with an extremely high end system like you linked to the quality of the initial dictionary is really important.