Humour could tackle that. I saw that behaviour around 3-4 in my DS, and I would bait him by intentionally mis-reading stories. It would start with a word substitution or two, and I'd ratchet it up into tangents from the main story arc.
A few reactions are possible:
1. She gets annoyed and intercedes to correct you.
2. She intercedes out of pride in her abilities.
3. She is amused and joins in.
To this day, DS6 and I still do goofy reading. (Hat tip to Dude--we still alternate for read-alouds--and I hope that tradition continues. Depending on the pacing of the book and our moods, that could be alternating chapters or two page spreads.)
One of his favourite games is to make word substitutions in a story using frequently occurring words. Great game, good for a challenge to working memory, and potentially even more fun when you mess up!
Another favourite is to insert a random word every X words. You can ratchet up the complexity by making rules about parts of speech, starting letters, or a theme.
Voicing and using accents is another fun way we shake up reading. You choose certain "trigger" words that cause a shift into a particular accent. So, for us, it might look something like this:
- "When": triggers posh London accent
- "Right": triggers Scottish brogue
- "No": triggers pirate accent...etc.
These might sound like ridiculous games, but they're a ton of fun and they serve to take the child's mind off functional reading performance. If your hypothesis that perfectionism is the root cause is correct, your DD will devote most of her processing speed to the game, with the bulk of the actual decoding and comprehension happening naturally.
Enjoy, and welcome to the forum!
