perf: Consider removing deepcopy

The use of `deepcopy()` in our codebase significantly reduces performance because of the large number of allocations it requires. There is no need for `deepcopy()` if the caller only wishes to read the data and not modify it. This creates a performance burden for readers to protect the interests of those who may want to modify the data. It would be more efficient to perform `deepcopy()` on the caller's side when necessary, rather than doing it implicitly all the time. We might want to consider documenting exported methods to indicate that a `deepcopy()` is needed if the data is to be modified. And remove preemptive `deepcopy()` from exported methods.