I have a 2009 Mac Mini, and I just installed Kodi 17 RC3 on it.
To my surprise, the videos looked choppy, as if Kodi is using software decoding. I tried using Kodi 16.1, and everything works as expected.
I checked that HW acceleration is turned on, and I disabled all suspects that are new in Kodi, like color profiles, dithering, resampling, etc. Still I get choppy video.
BTW, the hardware acceleration is named differently in the two versions: VDA/VTB.
Any ideas?