CEF was(is) in beta, that was something we wanted to try, we were never happy with the implementation of it.
Getting CEF to a point where its stable would be akin to writing a new player application, which is something we’d like to focus on instead. New cross platform player will be introduced in 1.9 series.
We’d recommend IE11 also make sure the registry entry for browser emulation is set to use IE11 - Enabling HTML5 in the Windows .net Player
Those registry changes should be done during player installation (from 1.7.8 version)
Can you give us an example of a webpage that is not working for you so we can try it?