A renderização do Flutter envolve três árvores — a Widget tree (configuração), a Element tree (os widgets instanciados e gerenciados) e a RenderObject tree (layout e pintura). Entender este pipeline desmistifica como o Flutter transforma eficientemente widgets em pixels.
As três árvores
WIDGET tree → immutable CONFIGURATION (what you write: the description of the UI)
→ cheap to create/recreate; rebuilt often (build() returns new widgets)
ELEMENT tree → the INSTANTIATED widgets; manages lifecycle and LINKS widgets to render
objects; PERSISTS across rebuilds (this is the key to efficiency)
RENDEROBJECT tree → does the actual LAYOUT, PAINTING, and hit-testing (the heavy objects)
→ expensive; REUSED and updated (not recreated) across rebuilds
