I've just inherited control of an old .xls file that my office uses, and I've been digging through to find out why this (relatively small - three sheets, none larger than 20x300 cells, no graphics) sheet is 6MB. We create somewhere around a thousand copies of this file a month, since each client gets a customized version, so it's a fairly substantial disk space hog.

I assumed it was some embedded macros we had, but digging into the file structure(by using the xlsx>zip trick), that's not it at all. Instead, there's a mountain of the following tags:

<row r="65536" ht="12.75" hidden="1" customHeight="1" x14ac:dyDescent="0.2"/>

There's one of those tags for every row in the document, from the end of the content, all the way down to row #65536. And I have no idea why. I've tried deleting all the bottom rows, in hopes that it'd start just using the default format, but that hasn't worked - unhiding removes the hidden="1" part, but the rest remains despite my best efforts. What can I do to eliminate this cruft and cut down the file size?

Thank you.