I already tested a lot of videos (local and UPNP) and I have seen artefacts but definitely not too often (Kodi and Himedia player) - not a big deal I would say.
Kodi 15.2 is jerking too much at the moment. For me it improved a lot by using WLAN, disabling MediaCodec (hardware acceleration) and enabling the caches as described before but this is not 100% fixing the issue - it is still stuttering for a lot of mkvs (not only at 23/24 FPS).
Good news is that the HiMedia Mediaplayer / eHomeMediaCenter (UPNP) is doing a good job for me (configured 1080p/60Hz and enabled 1080p24Hz / optical out). Did not see any stuttering for mkv movies up to now (local & upnp). One exception are a few TV series. The mkvs are 1080p, H264, 23,9762.. FPS and are stuttering using Kodi and the mediaplayer. VLC (MAC) and my WD TV Life are rendering these without any problem.