I am building an application that includes a UIWebView
containing a large number of images, CSS, embedded video, and JavaScript tap handlers. Scrolling performance
The guys at LinkedIn have done extensive work with UIWebView and HTML5 on their iPad application. Their entire feed which is heavy with images, texts and videos is rendered inside a UIWebView.
The following blog post should give you lots of starting points to performance improvements
LinkedIn for iPad: 5 techniques for smooth infinite scrolling in HTML5