This is really interesting. I wonder–would it be possible to listen to an audiobook or PDF at 800 wpm once one learns how to understand the screenreader "language"? Presumably the cognitive load would get heavy if the content were a stream of unstructured prose as opposed to code.
Yes, that is how I usually consume my content. Cognitive load is actually lower for unstructured prose compared to code, think about fiction for example. Code is much denser.
When I read to relax, it is for enjoyment, so I don't aim to read as fast as possible. This is why I still listen to human narrated audiobooks, since a good narrator adds to the experience.