I read kinda fast, and can read a 300page pbook in a about 2-3 hours if its a gripping tale. I read mostly by word shape assosiation ( I look at the shape of the words rather than the actual word, and ignore the smaller words -and, the, but etc) and rarely subvocalise. I have a vivid imagination, and 'cos of the way I read, I suck at spelling and grammar. I have been kicked out of speed reading courses (cos I beat the instructor), BUT, when I am racing, I retain very very little.
For retention , 300 pages in 4 hours is about average.
on the plus side, I can read a novel on the day before I see it's movie version....but I read nearly 15 - 20 books a month. (18 last mnth) I read faster on an E-device, PDA or Kindle at the moment.