so i think i've found a cause. I have a second display connected via dual link DVI.
when i have it set to 'displays have separate spaces' it makes systemuiserver grow.
I've checked that off, logged back in, and systemuiserver is been stuck at 11.1 mb.....in the other setting, it would have been in the 300 - 400 mb already
only issue is full screen apps and the fact that it blacks out the entire other display. been using better snaps tool from the MAC store. but that doesnt help when playing something like a youtube video and making it full - screen