I have had that feeling a few times. The first time I photoread the Cubase VST manuals (900 pages or so), the time I PR'd the Microsoft Encarta Dictionary, when I PRd Atlas Shrugged (I really should have rapidread it afterwards, I never did activate that book), and the first time I did a syntopic read (6 books on Game Theory). I have a feeling I'm going to have it again because I'm gearing up for some Direct Learning in different subjects next month.

I always thought it was like the adrenaline rush you get when you catch your second wind during exercise.