Ths is a known issue in OOXML library. Since the team is busy implementing features, the performance issue may not be fixed in 2.0.1 final release.
The main reason of the issue is because XSSF uses XmlSerializer as the serializer for OOXML document. However, XmlSerializer is not working as fast as expected. It's always slow. To fix this issue, we have to find a alternative way of serializing OOXML document.
The main reason of the issue is because XSSF uses XmlSerializer as the serializer for OOXML document. However, XmlSerializer is not working as fast as expected. It's always slow. To fix this issue, we have to find a alternative way of serializing OOXML document.
