[rpi 2] kodi use only one core while playing x265

[zebul666]

hi.

Trying to play 720p x265 is fine with libreelec on rpi 2. However, when I try to do the same in archlinux arm, the sound skips, the video is sometimes slow, and grind to a halt most of the time so it's unwatchable.

I found out that kodi only use one core at 100% in arch. while the 4 cores are used in libreelec. why ?
I tried to use the wiki suggestion that is true for x264 that is to disable hardware acceleration but that changed nothing.

I have cross-compile kodi with the only result so far to decrease the size of kodi.bin from 32MB to 18MB (not related to my question but why the size changed ?)

Any idea ?