Every URL visited from the Facebook iPhone app is done through a webview. Same with Twitter. Even if you don't have a mobile app, your website gets a lot of traffic from webviews. And yet, testing on webviews is challenging. There are significant performances differences between UIWebView vs WkWebView, and similarly for Android webview vs the new Chromium webview. And what about home screen apps?! In this talk, Steve Souders discusses the differences across webviews and how that affects performance of mobile web apps.