> Presumably Excel has to load everything into memory at once since it's immediately viewable, right?
Depends on the file format. An XLS or XLSB file can contain special markers for where each logical row starts, so it can randomly access rows; Both also can persist "calculation chains, which are a simplified dependency graph. The binary formats also store formulae in a parsed representation allowing easy scans to see what cells have to be inspected if a file needs to be recalculated.
Depends on the file format. An XLS or XLSB file can contain special markers for where each logical row starts, so it can randomly access rows; Both also can persist "calculation chains, which are a simplified dependency graph. The binary formats also store formulae in a parsed representation allowing easy scans to see what cells have to be inspected if a file needs to be recalculated.