[goodton]

if you need to software decode on windows, due to lack of hardware supporting h265(10bit), make sure to use a 64bit build of kodi.

 tried 64bit Kodi on Windows 10, still stuttering, not as bad, but still not watchable.

potplayer runs 4k without any issues, so i'll stick to that for the moment. 

Yes, it is true that although 64-bit Leia is already/will be more efficient in SW-decoding than 32-bit Kodi, those Windows-specific 64-bit players are typically even more efficient. Not an expert here but might be related to common codebase used for different platforms in Kodi SW-development.