Usually, the conversion takes about 2 second per page, however that might not be the case for all the PDF files. It might change depending upon the complexity and contents of the PDF files. Moreover, I would like to share with you that we have introduced merged Aspose.Pdf for .NET version, which provides the similar functionality as that of Aspose.Pdf.Kit for .NET, but also contains the features of legacy Aspose.Pdf for .NET.
You might want to try the merged version as well. If you think this doesn’t help in your scenario, then please share the input PDF file with us, so we could investigate the issue. And our team might try to improve the conversion speed.
We’re sorry for the inconvenience and looking forward to help you out.