1. Listening to speech at 450 WPM is a totally attainable skill for the sighted. It is not some kind of magical superpower that only the blind are blessed with. It's learnt by gradually increasing the speech rate and stopping just before the speech gets incomprehensible. For the record, I can't listen to text at 450 WPM and fully concentrate for long periods of time. Novels and other long pieces of writing I read at a much slower rate.
2. Processing visual information does take processing power. However, so does inventing and using coping mechanisms in a world that has been mostly made by and for the sighted. In most cases I rarely get any advantage of being blind. I just think of new approaches of performing as equally to the others as I possibly can.
For an audio only analogy, I would liken it to being in a room full of people at a party and trying to listen to one person vs being in a room alone with headphones. You should be able to process speech audio better and faster with the isolated input compared to the literally noisy one.
Or to put it the other way, there's a LOT of mental energy spent managing (especially filtering/categorizing) visual sensory information. Remove that distraction, and other senses get more processing power.
This is not to minimize the high performance of the essay author nor developer XXX, especially given the fairly sight-biased state of computing. But if you were to find some new change in your capabilities, with time and effort you could greatly enhance your performance in other ways.