This.

I was speed reading since Third Grade and remember making a deliberate effort to slow down in Junior High because I was not retaining enough information to write essays. During High School, I broke the curve on A.P. US History on an open notes final without having a single note to bring to class.

Auditory learning styles may require the subvocalization to succeed.

You don't want to break it in the sense that you stop doing it altogether. Just as lukev said, you would want to learn controlling it to your advantage - slowing down and speeding up depending on what you a reading.