Export Very Large Excel Hang IIS

At work we have to real-time generate a report(excel format) which involves a number of table joining. So to export into excel contentType 'application/vnd.ms-excel' is used, and data are written as table, looping each row of recordset data as table row.

Problem is when user hit export and attempt to open/save the file, file would then be downloaded at constant rate. But during this time, entire server would be irresponsive and in a hang-like state, this is expereinced by all users.

When they attmept to visit another asp page they would wait until the page eventually timeout. This will continues until the report was completely generated and downloaded by users.