As another really fast reader: if I get to the end of a sentence/paragraph/page and feel like I must have missed something, I just read it again. If you read really fast, it's not that much of a penalty. It's much like how slow typists will arrow back to correct typos, but fast ones will quickly delete all of the words back to the typo and just retype from there.
This is what I do (I'm OP). Normally, I wouldn't say my comprehension is hurt. But if it is, I just reread. You get a deeper understanding the second time through, and rereading is far faster than reading.
I've zombied myself through a few chapters on countless occasions. Sometimes I get into this mode where I'm just processing information and moving on to the next sentence like it's an entirely new work: process, understand, toss out, go on to next thing.
Sometimes that results in noticing that I don't even remember the last two or three chapters and have to reread.