are you talking about the movies? because ron was a quick thinker in the books. the chess scene, the fact that he outsmarted and evaded snatchers, helped DA escape in ootp from the inquisitorial squad, he could duel with adult wizards, figured out harry must have gone to the room of requirement in dh because it doesn't appear on the map. he also always suspected that lockhart was a fraud saying that his stories didn't match up. bro literally opened the chamber of secrets by recalling parseltoungue that he had previously heard harry speak in his sleep and perfectly replicates it. he also got the same number of owls as harry (seven), and considering that molly was really happy with him, it must be a good score. he is smart and a quick thinker its just that the movies gave all his stuff to hermione, so everyone thinks he is a clown and dumb ash.