I have several 4k rips that have a brief buffering popup with "high bitrate scenes", when playing them with the builtin player they play without buffering.
If it was only the testfiles I wouldn't be worried

and I know the chipset could decode even 400 Mbps without problem. I'm just a bit disappointed cause it is a full blown 4k player and I would expect it to play those "standard" 4k rips without buffering.
Will do some testing with newer Kodi.
Small update: Just tested with Kodi v17.5 "Krypton" and... No more buffering.
Off course I don't have the HD audio formats so not a real alternative... Maybe the buffering in Vidon is related with the audio streams., cause with Kodi I only have 2 channel stereo.