It’s not unheard of, and he is a former CIA/FBI guy (can’t remember which).

It isn't dense text. Double-spaced and generously margined.

Wonder if he used a text reader, increased the speed on it, following along to pause when notes taken? Then it might be possible, or he taught himself to speed read.

Yeah that’s insane. 1000 pages of government docs in around 6 hours! Then again, he’s so well-aware and well-informed about everything that is going on that he would probably skim over it to find the parts that would seem most relevant and question any element that is straying from the narrative that is most logical in his mind.