The framework layer of WPF is implemented in C#. WinUI is all C++, including the framework and the compositor that makes the DirectX calls.
In the framework layer, typical UI updates are faster because the WinUI data binding system uses code-generation rather than the reflection-like runtime binding system that WPF has.
WinUI also includes the rather incredible Windows.UI.Composition API’s, with things like ExpressionAnimation that enable lots of cool animations (like parallax, sticky header, or cursor-relative) at a stable 60 FPS.
Disclosure: I work at Microsoft on the Windows team.
In the framework layer, typical UI updates are faster because the WinUI data binding system uses code-generation rather than the reflection-like runtime binding system that WPF has.
WinUI also includes the rather incredible Windows.UI.Composition API’s, with things like ExpressionAnimation that enable lots of cool animations (like parallax, sticky header, or cursor-relative) at a stable 60 FPS.
Disclosure: I work at Microsoft on the Windows team.