New Post: Add rows at the end of an XLS file without loading it

Hi!,

I would like to generate a large XLSX file, by adding batches of rows in chunks at the end of it.
As of yet I found no way how to achieve this with PHPExcel. At 30.000 rows the loading and saving itself takes each over 20 seconds.
I wonder if there is a way to add the new rows at the end of the file without loading it into memory and save it with the new rows?

Thanks
Marcin