Have you seen a viable "alternative browser engine" that doesn't require javascript support these days?
It is not about "performing slowly" but about getting your app rejected from the App store because it violates an Apple policy of scripting languages/interpreters not being allowed. And also another one that forbids you from competing/replacing the Apple applications, i.e. Safari. So if you want to display a web page you have to use webview (i.e. Safari behind the scenes).
