In other words, when you modify the pivot table, Excel uses this cache instead of the source table. When you create a pivot table from your table, Excel automatically creates a pivot cache that holds a copy of your table in the form that is convenient to use for the application.
If you use third third-party applications you should use XLSX because binaries can’t be open outside Office Suite. It can be risky if you open a file that is not trusted and execute malicious code. If you save a file as an Excel binary, you can’t know it before you open it.
This way of saving a file make them easy to use by the third-party application but at the same time, they are larger in size.
