This app was mentioned in 1 comment, with an average of 1.00 upvote
If you are using Android for reading books, I would recommend any application, which can show you book with specified speed. I'm using AutoReader 3d (https://play.google.com/store/apps/details?id=com.webstunning.fc). As for me, speed more than 330-350 words/min will require from you quite deep concentration. Additionally. for me it looks like meditation when you need to put yourself in kind of "stream of conscious" mode.