Took a speed reading course years back. Still have my notes somewhere -- but, since I dread the idea of trying to dig them up, my memory of the key points is something like this:

1. Don't read aloud. Don't vocalize, actually or mentally, as you read. Maximum speaking speed is something like 250 words per minute (and comfortable presenting speed is three words per second). But your eyes can move much faster than your tongue.
2. Don't backtrack. Train yourself to take in the meaning on the first pass through.
3. Don't get bogged down. If you don't understand, leave it and keep going.
4. Don't move your eyes from side to side, but use your peripheral vision as much as possible. This is less tiring.
5. Preview the text before reading it -- scan through, with a focus on the beginning and ending of the entire piece, and on the first and last sentences of each paragraph. This is the concept of the "hermeneutic circle" -- that the parts are understood in terms of the whole, and the whole emerges from the parts. Once you have a framework and an idea of where the author is going, you more readily understand how each piece fits.
6. "Chunk" the material. Take in a phrase, or a line or more, at a time. You don't read letter-by-letter, and neither should you read word-by-word.
7. Practice makes perfect. Gradually increase your abilities -- to chunk more in one go, to not backtrack, to fixate less, etc.

There was talk of a trade-off between comprehension and speed.

There was mention that different sorts of texts require different speeds.

And there was a mechanical device that was something like a ruler, a metronome, and a treadmill. It would gradually move down the page, its tempo could be increased, and one had to learn to keep pace with it.

Note that this was just one particular course; different courses have different doctrines and methods.