Yes, it's most probably a video codec issue and usually animiated wallpaper apps activate video codecs in the background. Maybe a custom notification sound or ringtone also can cause such issues.
Can i change my(prl) settings to "LTE/cdma/UMTS auto" whit build.prop ? For better network. When i go in a room. Than my LTE goes to UMTS. But manuall i can change to LTE...and than it stay.