For me speed reading is more about building a mental model of what I'm currently reading. I was just a reading a light novel (very light reading) and I could skip over entire pages, because when you have that mental scene, skipping pages is like taking off your eyes of a movie for a few moments. You can easily recreate the missing context or read the parts over (akin to asking what you missed). I mostly do this for fiction book, as non-fiction are sometimes too dense to do this.
Another trick is to focus on a specific word. Some words I can recognize with the corner of my eyes, I could say. Which means you predict what comes after, and you skip over it and focus on the next word you don't recognize. You go back if what you're predicted don't make sense to what you're currently reading.
All of this is just for skimming. I don't read fiction to remember quotes and the likes, so I used it quite a lot there. I can read 2 or 3 books a day that way. While I can remember the majority of the story, I couldn't quote a single part of it.
For serious books, I read more carefully, and I revert to subvocalizing, but I'm often done with the sentence with my eyes (using my short term memory) before I even subvocalize the first three words. So it's not really a hindrance, although I have found myself needing to reread a specific part as I otfen speed read over it.