The goal of the reactive/declarative approach was never to be more performant than imperative code. The goal is to more easily build UI that is performant enough and functions correctly. With imperative UI code it is incredibly easy to forget an edge case in your update logic.
replyNot if you actually do MVC, so solved around 50 years ago.
reply1. The UI tells the model to change.
2. The model does the change and possible related changes.
3. The model notifies the UI that something has changed.
4. The UI updates itself from the model.
Alas almost nobody does MVC, despite calling what they do MVC.