There were a few reasons to move away from CefSharp, but yes a main reason was indeed performance. It tends to be quite resource hungry (which was a complaint of some users!) which is not ideal. It was also a bit of a pain running into mismatched versions within different host applications.
While working with xaml is quite different from working for the web, you can still get great results. Check out the docs for our UI here or this short demo video in Rhino! This approach hopefully also makes it easier for people to build new connectors by making it simpler to hook them up to this UI.
The main limitation I see at the moment is that it is not cross platform, but we will cross that bridge when we get to it