[tokyodude]

And yet the WinAPI is not actually preformant for types of apps that an ImGUI excels at

There's best case for Retained mode GUIs and best case for ImGUIs. ImGUIs excel when lots is changing. In a scrolling mobile app the entire page is being re-rendered constantly as the user moves the page up and down. GUI widgets get created and deleted, data gets marshalled in and out, various algorithms are applied to try to minimize re-creating stuff, all code that doesn't need to be executed in ImGUI mode code.

There are tons of cases where ImGUIs win in perf. In fact the reason they are so popular with for game dev is exactly because they vastly out perform retained mode guis. There's a reason there are 100s of books and 1000s of blog posts and articles trying to get retained mode guis to run smoothly. They almost always fail without lots and lots of specialized client side code to try to minimize GUI widget object creation/deletion, reuse objects, minimize state changes, etc, all that code disappears in an ImGUI and they run at 60fps where as all the retained mode guis struggle to get even 20fps consistently as they hiccup and sputter.