I have to provide data exports from *Mathematica* to CSV format and it is very slow compared to other formats as can be seen in the following table:

* JSON, 15 sec, 8.4 MB
* TXT, 23 sec, 5.6 MB
* XLSX, 37 sec, 3.0 MB
* CSV, 704 sec, 4.4 MB

Can somebody give me a hint on how to speed this up? Or an explanation why it is so slow?