For a moment it seemed to me ... but not, unfortunately, you're wrong.
Any variants of the builds have low performance on iOs. And ok on android.
In this step, you remove the files that specify to use WKWebView. So you are effectively disabling WKWebView yourself.
For the specification of plug-ins is necessary and sufficient config.xml file. I did not delete it. I removed files relating solely to configure IntelXDK project, and created them again in IntelXDK self. Besides the convenience, what's the difference where to create them?
What about PhoneGap build which does not contain *.xdk in principle?
By your logic, it is impossible to enable WkWebView through PhoneGap.
Via Plugin Management add all the necessary plug-ins including WKWebView, File and Httpd
In this step i return all information about WkWebView that is contained in *.xdk file from Construct2. This a procedure of adding plug-ins officially recommended by IntelXDK. Could you explain in more detail why the addition of WkWebView such a way must not work?
I tried through Construct2 *.xdk file - absolutly same result.
Opened as a bug: