I'm a really fast reader (in my native language) I read faster than anyone I know irl, in any environment. But as other people has already pointed out, I usually skipped a bunch of things and had to reread it to remember all the details. I don't know how I first did it, I remember doing this as early as in 2nd grade. I just somehow pick out the more important word. This should be easier in English (I think) as you can just read the longer words. The most important thing is concentration, you're in the book, nowhere else. Excitement helps too, when I'm really excited, I just naturally started it. Practice is also important, the more you do this, the more you get used to it. Although this is starting to become a problem to me, while some in this thread say they can stop, I can't. When I don't concentrate, my eyes flew through the words, I missed a lot of things. When I do concentrate, I read faster, and I still missed a lot of things. This might depend on the person, but just know that there's a possibility that you won't be able to go back.