You can store the report result in Excel buffer sheets when exporting to Excel format. To do this:
The default size is 1, which indicates that 1 sheet of the report result will be allocated to the result buffer, while the other sheets will be stored onto disk. If you have enough memory, to improve performance, you can increase the Excel buffer size to store more sheets of the excel format report result.
Note: The Excel Buffer Size property takes effect only when the Data Format option in the Export to Excel dialog is not selected.