Okay, I see I've been using words in an idiosyncratic way, so I'll just dump out my thoughts on the subject, most of which came from Eliezer's author notes:

To write a character successfully, you need to show that character acting in ways in which it would be plausible for them to act. To write a character who's smarter than you - who would plausibly choose courses of action and speak lines of dialog that wouldn't occur to you - you need to cheat. Smarter-than-Author-Intelligences can think faster and remember more, but they can't be better than you at seeing the connections between the facts at their command. If they're Emmett Brown, they can invent amazing technologies, but the scientific explanations for them will be gibberish. If they're Sherlock Holmes, they reach startling and true conclusions on the strength of bad evidence.

The movie Gattaca is full of artificially-selected superbeings who never speak a single witty line. That's the difference between a character who's supposed to be smart and a character who's successfully written that way, between telling and showing. Eliezer may have intended for Quirrell to be smarter than him in some sense, but he hasn't been written that way, because he couldn't have been.

Unless all you meant by 'horsepower' was thinking speed, in which case you might be right. Dunno.