Kwiboo: I suspected that it is software decoded, however the cpu usage doesn't exceed 70% (of 400%) so not even a single thread is completely used.
The stutter is also continuous with no apparent spikes which leads me to think it has nothing to do with CPU performance limits. Also the stutter becomes way worse when setting the display refresh rate lower (for example 24Hz/25Hz which are the source frame rates for these cases).
Deinterlacing turned off doesn't change the observed behavior.
Do you have a Rock64 and if so do you see the same behavior on MPEG4/Xvid/DivX content?
Edit: The jitter/framedrops/continuous stutter is also visible in the Kodi UI