The tappable area is a very valid concern. Currently, it is managed entirely by the browser, based on the element dimensions. At some point, we are planning on a research if we can't improve that behavior somehow.
Unfortunately, I can't provide much assistance for the second problem. Perhaps the PhoneGap support may know more about it.
Our research so far shows that transitions performance is largely related to the view contents - large lists tend to be sluggish, for instance. In-depth review and examples about how to speed things up are the focus of our next release.
Native iOS apps do not allow text selection by default - you may consider using input elements for that.
the Telerik team
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