You're using it wrong. No really you are.
Give Fabe 5 access to a test database with some data, or even restricted access to your live DB and tell it to optimize then.
I've had stunning success optimizing for performance this way. In a single day, I made the core part of our app 2-3x faster.
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Thats fine but then Fable 5 should have requested this information instead of blundering along. So why didn't it? An expert human asked to do the same task would have surely asked for the additional data.