I reflashed v483 and upgraded it to v496 using OTA ZIP, set everything again, then set limit for background processes in Developer options to 3, and it seems that the stuttering is almost gone. Hopefully it will stay like that1. Videos played on it (thru IPTV apps, Netflix etc) are not very smooth, I can see considerable stuttering in movement. It seems it is much smoother when using the same apps on Fire TV Stick (4k Max) connected via HDMI, but only when I have TV Stick's output set to 8bit colors - if I set 10 or 12bit, it stutters too. Is there any way to reduce that stuttering? Or is it caused by too slow CPU in the TV, that doesn't have enough power to play 24-25 fps content on 60 Hz TV with the postprocessing it has, and there can't be done much to fix it?
EDIT: Unfortunately it stutters again. Perhaps it depends on app, tasks running in background, or CPU temperature..