Comcast's newer IPTV/X1 boxes are somehow worse, as they have 100x the processing capacity of the old Motorola/Cisco boxes, but use it to run a slow as molasses JS SPA. The Netflix app runs at probably half the speed of the Apple TV (or the Fire TV Stick) and even Comcast's UI can sometimes take upwards of 1-2 seconds to respond to a button press.

X1 uses a cloud-based UI, kind of like X-Windows client and server.