Performance writing large excel spreadsheet to browser

We are using the Aspose.Excel component to generate a large Excel files (20.000 rows, 43 columns) in a web environment. Building the excel object in ASP.NET takes about 15 seconds (almost no formatting). After this we want to send the Excel file to the browser using the following statement:

excel.Save(filename, Aspose.Excel.SaveType.OpenInExcel, Aspose.Excel.FileFormatType.Default, Response)

This takes about 140 seconds !, is there any way to speed this up ?

We will try to optimize the performance contiuously. Could you post your sample code to create your large file here?

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The new version doubles the speed in my machine.