The app works fine after it starts but it consistently takes about 60 seconds + high CPU before my code starts executing. When I run the app from Visual Studio or via the old click once install it starts instantly.
The .msix file is about 130 MB. The app has a dependency on the Crystal Reports runtime. I used the MSIX Packaging Tool to create the package for the Crystal runtime, then I added my app to that package.
I'm stumped.