Poor Performance in Premiere Pro CC 2018 (Ver. 12.1.X) with ProRes footage

We have recently found an issue with Premiere Pro 2018 version 12.1.X with ProRes footage causing up to 35% longer export times and a 50% drop in live playback performance with both ProRes 422 HQ and ProRes 4444 footage. Unfortunately, currently the only fix appears to be rolling back to version 12.0.1 of Premiere Pro 2018.