Spreadsheets in Documents now load pivot and list data only when it is actually needed, such as when the relevant sheet is opened or filters change. This reduces unnecessary server calls and should make complex spreadsheets and dashboard templates open faster without changing user-facing features.

Various optimizations to lazy load data sources as much as possible.
The main idea is to load data sources only if really needed. If the pivot is on Sheet2 but you never go to that sheet, the data source should never be loaded.

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