A cuantas palabras por segundo puedes leer y mantener una buena comprension? 500-600-700 ?
Psychologists have observed that practice enables a skill called "whole sentence reading." This means that your brain gets smart enough that it can take written words in faster than you can say them, one sentence at a time.
This is no different than when you first started to read, you sounded out words. Then you learned to recognize words without sounding them out.
So read a lot; practice. It will come.