It will help if you specify the platform you are testing on. That said, jQuery Mobile uses the native platform scrolling, so it will be faster I presume. However, this makes using application layouts with header and footer or scrolling containers a bit trickier to accomplish. This is why we decided to use a custom scroller, though we don't experience any slow speeds with it (except on older Android and BlackBerry phones). I've also tested form interaction with our framework and jQuery Mobile and didn't notice any change in keyboard popup speeds. Can you isolate those issues in a sample page, so that we can reproduce them? Thank you in advance.
the Telerik team
Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI