I am not sure why you want to empty the info structures, but if i want to empty the info structures then i would use tcode SARI-->Status-->status per info structure-->delete info structures. This would be much faster to empty the info structures.
AS_AINDDEL_DATE this report is slow because it has to get the specific date and get to delete the archived information from the structures. You can use this report only if you have a requirement to delete the info structures for a particular date.