Importing a document could result in a big UsedCellRange due to the big range of the imported DataValidationRule cell property. The UsedCellRange calculations should ignore this property. This could lead to a performance diminishment when exporting.
Hi, The issue is fixed and is included in today's LIB release (v.2016.2.627). Do not hesitate to contact us if any issues or questions arise. Regards, The Telerik Team