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When a user requests an Excel document, you can first check to see if there is new data. If there is, you can generate a new report and save it to disk. You can then stream that file to the user. We have a KB article which describes how to stream a file to the user that was previously saved to the disk with ExcelWriter.
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Apply Styles to areas and not cells
Every time Cell.Style is accessed, ExcelWriter instantiates a separate Style object. To reduce file size bloating, we recommend using Global styles and setting styles on groups of cells. For details, see Effective Use of Styles.
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