I don't have links to studies but last time I checked and from anecdotal experience reading speed with high comprehension is limited by information throughput in the brain. It's also why languages spoken faster carry less information per word, because the limit is information processing. To experience that if you are a good reader, you can try to speak out loud a sentence while memorizing a second sentence and see that you'll not have process and understand the words until you have spoken them, even if you have read and stored them (short sentences like in TFA, obviously doesn't work on HN).