Performance is less of an issue than it was, but it still exists (though the great IOS8 news is that in-app webviews finally get Nitro[1]). The larger problem, IMO, is UI. You simply cannot recreate native UI in a web view.
But there are some interesting frameworks out there that blend native UI components with web views - it can work well, and is used more than people often think (in Instagram, for example). As with anything, it's a tradeoff. If you want to make cross-platform a priority, having your main views be web-powered can save you a lot of time, even if they won't be quite as good as native ones. But I maintain the non-HN crowd will be unlikely to notice a slight lack of polish - the standards in our echo chamber are artificially high, IMO.
But there are some interesting frameworks out there that blend native UI components with web views - it can work well, and is used more than people often think (in Instagram, for example). As with anything, it's a tradeoff. If you want to make cross-platform a priority, having your main views be web-powered can save you a lot of time, even if they won't be quite as good as native ones. But I maintain the non-HN crowd will be unlikely to notice a slight lack of polish - the standards in our echo chamber are artificially high, IMO.
[1] http://9to5mac.com/2014/06/03/ios-8-webkit-changes-finally-a...