The current CEF version in BeamNG is from October 22, 2015. That said, I do suspect that the UI responsiveness might improve if CEF were updated in a new BeamNG version.
Maybe they could update to CEF sharp, but then again they probably don't want to write everything again, I just like C# much better than java: https://cefsharp.github.io/
From some reason I was thinking UI coding and mixing up things, some days even I don't understand myself
Not as easy as it sounds. Updating can break a lot of things (like, a lot of them). The changes are also not that interesting to take that huge risk, so yeah.
So is that you saying it isn't currently being worked on or it is being worked on just don't expect it in the next update?
I said multiple times, in different threads, that we are working on UI stuff that has no been announced yet. We will do that soon-ish. To make it in clear words, we are not done with the UI, we have quite some works being done and to be shown yet.