Spreadsheet::ParseExcel will have issues with very large spreadsheets. We commented out a number of things he was creating and found a 50-75% savings in RAM usage.

Also, ParseExcel and WriteExcel have complementary issues with formulas. ParseExcel will only read the value and WriteExcel will only write the formula. Excel itself can support either. Just don't be surprised if you use Excel as an intermediate format and get burned.

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.