Speed reading is explicitly trading off speed and comprehension. It takes advantage of the fact that we need to see a lot less of the text to pull out certain ideas than we think we do.
Not exactly. Speed reading has a lot of tactics that don't trade comprehension for speed. You said below that you pull in groups of words at once. Speed readers do that by looking at the spaces, which allows our brain to group words together. I started doing this when I was younger and got an immediate significant boost without practice and with no loss of comprehension.
What does your comprehension test at? It's not uncommon for speed readers to test at high comprehension with your reading rate.
It sounds like you claim to read fast, but then have to take extra time to digest, so if we add your digesting time to your reading time and count that total as reading time period, it's not actually that fast at all.
It's a skill that can be learned, but likely you self-taught and simply don't remember learning it.