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the facebook app used to be slow partly due to the fact that the devs working on it had no idea what they were doing (at the time, Facebook really stepped up their game lately).

The dev team at my ex company built a demo to show that the same app could have been made to perform acceptably using the right strategies.

https://www.sencha.com/blog/the-making-of-fastbook-an-html5-...

> It's almost identical to the system browsers now. Facebook's comments about HTML5 were back in the dark ages when the webviews generally used horribly slow software rendering and didn't have JIT for Javascript on iOS.

Incorrect at least as far as Android goes. Android's WebView literally was the system browser until Chrome was released complete with the JIT since Froyo (V8) and hardware rendering since Honeycomb. And the first several versions of Chrome on Android had much worse performance than the old WebView did.

This aside the bulk of HTML content is still software-rendered. It's software-rendered into tiles which are then GPU composited. It's a different story if you use <canvas>, but at that point you aren't gaining much by paying the browser tax so why not just drop to C++ and write GLES directly and get like 10x the performance?

That aside while there have been improvements in JavaScript performance, HTML/CSS & rendering performance really has not improved much if at all over the years. Browsers are still dreadfully slow to actually produce pixels compared to any other UI toolkit.

Does WKWebView work with file:/// urls needed by Cordova?

No, but there is a drop-in plugin that adds a webserver and converts your webview to WKWebView: https://github.com/Telerik-Verified-Plugins/WKWebView

It has a few limitations, but it's quite nice for games.

Check out https://github.com/Telerik-Verified-Plugins/WKWebView

Last time I checked (a few months ago) you couldn't use file:/// with a WKWebView at least on iOS8. Apparently, latest iOS9 beta allows you to load a local file.

Is there a reason they don't ship with a simple web server to server out the static files, similar to `python -m SimpleHTTPServer`?

The Android Cordova platform used to do this by including OkHttp but they moved away from that because it's now unnecessary.

Why would they want to? Both platforms have webviews that can render HTML from a file, or passed in strong form, or whatever you like. Why point it at an internal web server? If anything, it'd add overhead to the system that's unnecessary.

Apparently WKWebView does not support loading from file. That's why he suggested wrapping it in a localhost HTTP server.

> the Chromium webview on Android 5.0+

The Chromium based webview is available already in Android 4.4. So about 50% penetration at this point. It is indeed a huge boost to performance.

Oh, good point. I mentioned Android 5.0+ because the 4.4 one is missing some major features including IIRC WebGL, Web Audio and WebRTC, which still rules it out for some use cases (such as a game engine).

> radically changes the performance story

So that it's only 100 times slower than a native app instead of 200 times?