How much time is this taking to load and what is the indication that the issue is related to the video controller and not to something else in your system?
What has been changed to notice that the amount of time this takes to load is different? Was being faster before?
Are you seeing any other slow performance in the system or this only applies to UAC?
It's about three seconds which is very annoying. No problem if I force UAC not to dim.
I have no problem with AMD/Nvidia graphic cards even onboard.
And it's only about UAC