Should I declare converters in App.xaml or as a per-file resource?

Question

When declaring converters in a WPF application, should I:

1. Declare all my converters in the App.xaml (i.e. in

Answer 1

I have a ResourceDictionary that declares several commonly needed converters, such as a bool-to-visibility converter. I reference this dictionary directly in App.xaml.

I declare other converters that are more specific to a given situation at the Page/Window-level (or in a ResourceDictionary referenced by a Page/Window).

I can't answer the performance question definitively, but I would be very surprised if it made a practical difference in load time or memory usage. Declaring a converter is basically an object instantiation, so it should be very efficient and use very little memory, but I haven't done any profiling to compare app-level vs. window-level performance.