Ott M8 s802 4k Android Box and Youtube 1080p?

Hi guys, I recently bought an M8 OTT s802 4K Android Box and for the most part am happy with it, But iv'e noticed Youtube videos really play like crap.
I was wondering if the stock Rom that comes with this Box is still the best one for this device or is there any better/more optimised Roms out there that are (play Youtube vids 1080p 60fps) better?

Thanks..