I'm curious if my hypothesis is correct, but can't test it myself just yet.
This chapter and last have many prefixes that combine many letters. The groups electr-, intr-, and ship/short. On average, 3 sounds combined into one shape.
My theory is fast writers will find later passages faster than earlier ones because of this.
I suspect that for those of us still on their first pass of the books, the newness of the prefixes (compared to familiarity with words from earlier chapters) will offset the effect.
(Thanks to the person who recommended I put the pen away for now. Quiet time for writing is out of the question for now, but it's easy to pick up the book instead of another book over breakfast. We'll see how it goes.)