It's actually quite easy, you probably either just don't watch porn often or else you don't get particularly attached to which performers you're watching.
Some I memorize because I like them so I seek out their material. Others I memorize because I really, really don't like so I memorize them so I can more easily avoid their material. In the case of Mia Khalifa, she got famous because she was I think Lebanese born and dreamed of becoming a pornstar but received death threats from many people in her home country for expressing said desire.