A bit of both. At the time of making nUI 5 Scott wasn't aware that the druid boomkin form used that bar, clearly not having a druid at the top to test it I guess
He's aware of it now and I believe it will get sorted for the nUI 6 in some form or another.
Hmm, framerate that bad ? The only framerate issues I have ever had is when I am in a raid in raid frame mode. I switch down to party frame and the framerate rises, which is understandable seeing as it doesn't need to deal with so much information that way. I believe Dalaran has been the bane of the fps existence so if that was where you were it could be a too much information problem again.