The improvement doesn't necessarily come from the cordova side of things. That's still all the same old webview that gets wrapped up. The real difference is achieved with everything else that gets used to build the app. The Ionic framework avoids DOM manipulation where possible and enables hardware accelerated animations. Both these things is possible on top of plain cordova, but Ionic makes it so much easier and they have already done the hard work of figuring out what is going to perform best inside that cordova wrapped webview.