On the other hand, I really doubt Eliezer's vocal chords are doing that, because he reads at least three times more quickly than I could possibly speak no matter how many times I'd rehearsed the words

I bet most people read much faster than they could possibly speak, and most of them subvocalize. One possible reason is they skip all the filler that doesn't help comprehension. I don't think I subvocalize whole words, and I skip many. Then there's skimming which is a completely different matter.