Raspbian Kodi, DVB-T2 TVHeadend PVR and CPU at 100%

Hello, I’m having a problem and I cannot find a solution so I really hope you can help me: when I stream an HD channel on TVHeadend from my attached DVB-T2 stick the CPU goes to 100% and the video gets very jerky and unwatchable (SD channels work fine). More in detail the setup that I have:
– Raspberry Pi 2 with Raspbian Jessie, kernel 4.4.21-v7+
– Backend is TVHeadend 4.1-2247 (github build)
– DVB-T2 Stick is a Geniatech T230C (newer version of the T230, also known as August T210, driver Silicon Labs Si2168 compiled from here: https://bitbucket.org/CrazyCat/media_build )
– Kodi 16.1 (github build): MPG2 and WVC1 codecs purchased and enabled; /boot/config.txt contains gpu_mem=256; video hardware acceleration MMAL enabled;
– PVR Frontend is TVHeadend HTSP Client 2.2.12

When I select an SD channel it works perfectly, when I select an HD channel the CPU goes quicky to 100% and I can’t watch the channel. When I watch the HD channel on my Windows computer with VLC it works flawlessy (so I guess my problem is not with the backend but with the frontend/kodi).
I will attach a Kodi log file and a screenshot that I took in here: http://www.filedropper.com/kodilog
What am I doing wrong?