I'm a pretty fast reader, never timed how fast though. But to me speed reading has always seemed the preserve of people who don't really enjoy reading. Otherwise why would they want the chore to be over so quickly? I can understand wanting to read quickly if you've got to read for work, so for skimming through journals and things it's handy. But if you seriously want to remember what it is you've read then the key is repetition, not speed.
If a book is worth reading then it's worth spending time over and giving some thought to what's going on as it happens, not just racing through to the end. Yes, War and Peace is a hefty book, but to look at it as something to get through as quickly as possible I don't think is the right attitude to take. If you enjoy it, then you'll find you read it faster anyway.
As for vocalising words in your head, I don't think I do that. It's a hard thing to analyse, and a harder thing to explain, but I think I take in whole sentences rather than words, and then that is translated into 'action' in my head, pretty much instantaneously, and as the story progresses, so do the images in my head.