XL File Size decreases when saved by Excel App

1. I generate an XL report using SF XLSIO
2. I output it to a file (size = 500K)
3. I open the file in XL
4. I save the file overwriting it
5. The file size is now 281K

Is Excel doing some kind of optimization and is there any way I can figure out what it's doing so I can possibly address the issue in my report generation?

Thanks

Hi John,

Thank you for your interest in Syncfusion products.

I am afraid that I am not able to see the problem. Could you please try running the sample linked below and send us the modified sample if you still see the problem?

http://files.syncfusion.com/samples/XlsIO.Windows/F82241/GenerateExcel.zip

Regards,
Geetha