A customer reported that it took more than 10 minutes when he used Aspose.Pdf to convert an XSL-FO file to PDF document. Customer thought that it's a performance issue with Aspose.Pdf.Save() method but when we digged more into this issue, we found that it's not any performance issue with Aspose.Pdf. Infact, his .xslt file was trying to access a network resource that was unavailable to that server. It was an interesting case so, i think, it's better to share it with everyone that a possible performance failure may also be caused by a network path failure.
Another issue that may cause performance failure is XSLT in .NET 1.1. Sometimes, it takes longer to convert XML with XSLT. That is a bug of .NET 1.1. If you try the same code with .NET 2.0 it works well.