I've been exploring use of the Spreadsheet control. I followed an example which shows me how to define the provider and read from an XLS file in App_Data folder of ASP.NET application. Uses latest versions of UI/AJAX, VS2015, Azure, etc.
I am finding that simple spreadsheets load reliably.
Medium size ones take a few seconds to load, and then show a blank sheet, no error message.
See attachment for this error.
Large size ones take a long time and timeout.
I am wondering whether there are severe capacity and/or performance issues with the Spreadsheet control, or this behavior is a side-effect of reading a file within my app's directory.