The Apple Afterburner is a ProRes and ProRes RAW accelerator card that is an optional add-on accessory available in the 2019 Mac Pro. It supports playback of up to 3 streams of 8K Pro-Res RAW or 12 streams of 4K ProRes RAW.
Adobe says that Premiere Pro supports decode acceleration of ProRes 4444 and 422 codecs using the Afterburner card, but ProRES RAW acceleration through the Afterburner card is not supported at this time.
The Metal renderer must be selected for use in the applications (this is already the default setting):
After Effects (Beta): File > Project Settings… > Video Rendering and Effects > select “Mercury GPU Acceleration (Metal)”
Media Encoder (Beta): Preferences > General > Video Rendering > select Renderer: “Mercury Playback Engine GPU Acceleration (Metal) – Recommended”
Premiere Pro (Beta): File < Project Settings > General > select Renderer: “Mercury Playback Engine GPU Acceleration (Metal) – Recommended”
Adobe is seeking Mac Pro users with an Afterburner card to test the ProRes 422 or 4444 support to improve the feature.