Hi,
These files are not so large, but they contain CJK characters and uses some CJK fonts, although I'm not sure this is something to do with this issue.
Attached please find the sample PPTX file that took very long time to convert.
Environment:
* Windows8 / Windows Server 2012
* Visual Studio 2012
* Aspose.Slide for .NET 7.6.0
Code to convert:
PresentationEx presentation = new PresentationEx(fromPath);
presentation.Save(toPath, Aspose.Slides.Export.SaveFormat.Pdf);
Best Regards