MX2: Fuzzy 1080p 5.1AAC video when upgrading from OE 4.2.1 to 5/6

[taitelman]

I got the a MP4 video file and it ran OK on my laptop.
then put it on my MX2 + Android and the video had performance issues in the first few minutes. one of the CPU was 100%
installed OE 4.2.1 and the video was excellent (both CPU were 30-40% at most)
installed OE 6.0.0 for MX2 and the video sometimes get occasionally fuzzy pixelizations
as if the codec is bad (but we know its not).
Tried to remove amlogic Kodi HW acceleration and the video was running in slow-motion but was clean and nice.
anyone else saw same effect ? was there any change in the accelerator ?
BTW:

1. tested same video file on MX3+Android5.1.1 and it ran with no issues.
2. tested on S812 + OE 6.0 : problem reproduced. the player had difficuties decoding the movie.
3. tested on VLC on desktop: all is ok.
   will check the logs soon. but something in the Android native player is better .

[taitelman]

the file video codec is H.264 MPEG4 AVC part 10
1920x1080
fr: 23.976024

audio: MPEG AAC (mp4a)
3F2R/LFE. sampling: 48Khz