My reading speed is so variable that giving a single number for it would be very misleading. It's certainly impaired for much of the time.
Is that because of my ASD or not? Well, here's the reasons why my reading speed is impaired:
1. I often get hung up on unclear or seemingly incorrect details in what I read. It's hard for me to continue reading until I've cleared the block, which could take a minute or forever. My reading style is extremely linear, I can't easily skip around or "speed read," when I do that I feel I might miss something. That seems to be down to the Aspie tendency to hyperfocus on the detail at the expense of seeing the overview.
2. Often I catch myself failing to turn the written words into thoughts. I turn them into spoken words in my head, but that's as far as the process goes. To get round this, I usually have to force myself to write my own version of the material as I read it, in my own words. This works quite well, but naturally it slows me down a lot. I don't know what that is. Could be ADD, or maybe it's the Aspie thing of finding it difficult to read and comprehend stuff that I have no natural interest in. After all, that seems to be what the educational system is all about. My education certainly was, and that was when I first noticed a problem with reading. Possibly it got me into that awful habit of reading without turning the words into thoughts. It sometimes pervades my attempts to read books about subjects that genuinely interest me, though there are a few such books that I've managed to read pretty quickly with no difficulty.
3. I get daunted by lengthy texts. I keep feeling that it's going to take forever to complete the mission - naturally, being aware of the reading problems I've described, it's a reasonable thing to feel. And in my experience, most books are largely made up of unnecessary woffle, which makes my brain keep wondering why I'm wasting my time. I've often said that most books would be a lot more accessible to me, and just as informative, if they were condensed down to clear, concise pamphlets. It could be a product of ASD - I recently heard that Aspies have a tendency to "cut to the chase," but I'm not sure.
4. Related to the above problem, I have trouble with long paragraphs. My eyes get lost in the wall of text. If the paragraphs are a few lines each, it divides the work up into manageable chunks. Probably the reason I like WrongPlanet is that so much of it is presented in a bite-sized way that I can deal with. I've read here about Aspies who hate walls of text, so again maybe it's an autistic thing.
Summary: my average reading speed is low, but it depends on a number of factors. Some of my reading impairment is very likely due to ASD, and I suspect all of it might be, but I'm not sure yet.