I have been a long time AppleTV Channels user since the original release and for the last year or two I have seen a slow decline in overall usability.
The app when entering the guide always hangs for a long period of time. This occurs with or without PIP enabled.
Browsing the guide will randomly hang as well... user input is ignored as if the app has locked up... after a period of time has passed it then responds to input but only after processing all previous input commands as if they were buffered.
Playback stutters with default decoder.... have to manually specify legacy.
Overall the user experience has declined. I have tried deleting the app and reinstalling it from scratch.... made no difference.
Also with the default driver I am not seeing dropped frames but it stutters... not smooth at all.