File opens slowly, uses 1.5GB of memory

Created originally on Bitbucket by knightjimr (James Knight)

I'm trying to open (for reading and writing) a small 90kb Excel file, that Excel opens immediately, but openpyxl takes 1-2 minutes and uses 1.5GB to open. It looks like the file contains row and/or column formatting, and that is triggering openpyxl to replicate an enormous number of cell formats (even though none of the six sheets in the file have more than 100 rows or columns).

It is a submission file for a public database, so I'm not able to redo the structure. Is there a way to get to a file that doesn't trigger this issue (I've already tried and Excel format cleaner), and/or could you see if openpyxl could read it quickly?

This is happening with version 2.4.8.

Attachments: SubmissionTemplateFull_07252017.xlsx