A lot of this deepCopying was just not necessary. This removes the
deepCopying from all field hook operations where I think it's 100% safe.
It does not remove all deepCopying, especially in areas where the input
data was deep copied, and that data pre-modification is then used after
the field hooks have run.
In these cases, further execution of the hook might be intentionally
expecting the unmodified version of that input data
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