How to debug slow Office application interop constructor?

Question

I have an application which deals with excel. Recently I encountered a problem with very slow creation of Excel object.

I\'ve recreated the issue with this s

Answer 1

I don't think the problem is with this constructor. Try to create the object dynamically:

var obj = Activator.CreateInstance(Type.GetTypeFromProgID("Excel.Application"));

Then cast it to Microsoft.Office.Interop.Excel.Application:

var xlApp = (Microsoft.Office.Interop.Excel.Application)obj;
MessageBox.Show(xlApp.Name);

I'd expect the slow-down to move to the Activator.CreateInstance call.

Anyway, you can try to work it around by placing the following into you app.config file (more details):

I'd also suggest to make sure you're running the latest VSTO Runtime and the latest Office PIAs.