I've been using iPhone since 3GS and historically, all latest iPhones are very fluid and smooth with the latest iOS. There wasn't one generation that has any form of "sluggish" except the 6+ now. One of the key reason why I prefer iPhone is because of it's "smoothness" and responses are spot on, snappy. Of course I would love that the 6+ have these characteristics as well Maybe Apple should have used A8X on the 6 plus instead? That little lag is surely a turn off in my opinion.