A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
I'm having exactly the same kind of problem, fully related to using existing excel files made with Office 365 previous release 2015 and that were being managed without any issue at the time.
I am on a Win 8.1 pro laptop with 16 Gb of Ram...
Maybe there is a relation with images embedded inside the file, but not so sure.
I have run the scan utility above and the only thing I saw was a warning about an error on "outlook excel previewer", so I made the registry correction (follow the links that are in the scan utility results)
so not I no more am having any warning after scan,
BUT unfortunately it has not solved my "non responding" issue and slowness in Excel
Regards