Choppy playback of Blackmagic 4k mov files after upgrading to Premiere 2019

Since I upgraded to Premiere 2019 (whether 13.0.0 or 13.0.1), the MOV files of Blackmagic 4K Production Camera play extremely bad, to the extent that I have had to reinstall Premiere 2018. Has anyone encountered the same issue?

I am editing on an iMac Pro 2017, with a 16 GB Radeon Pro Vega graphic card.