There is no ion-button component but we do remove the delay on button and a elements. For accessibility reasons we recommend always using these for (click) events. If you place a click event on a div it will still get the delay. Last time we spoke to Angular about it we were told it was not possible to grab the click event on a div and therefore the delay stays.
Some info on items: http://ionicframework.com/docs/v2/api/components/item/Item/