2x feels a bit unnatural. Speed-wise 1.5x is probably the most ideal but personally, I think nothing beats his natural lulling (non)speed. It's just so calm and peaceful. And eventho he talks slow, he's very on point about what he says and paints a very vivid picture with his every word so it's never boring. 無駄又は空の言葉はないけれど急ぎ感も全くない所の故に素晴らしいストーリーテラーだと思います。