Resolve Fusion render cache does not play in realtime

When playing a cached sequence in the Fusion page of Resolve 16b6 (and previous versions of Resolve 16 beta), I generally get around 8–14 fps, making it very difficult to preview how a shot will appear when played in realtime. A single cached MediaIn node showing in one viewer with the other viewer blank is getting around 14 fps (MediaIn frame size is 1080p; original source media is 4K CinemaDNG). I am able to play a 960x540 image sequence at near realtime when it is the only thing showing in a viewer. Having different nodes displayed in two viewers (both cached) tends to slow playback performance substantially.

Cached frame playback works as expected in the standalone version of Fusion 16 beta.

I am on a 12-core Mac Pro 5,1 (High Sierra) with 32 GB of RAM, a GTX 1060 6 GB (Resolve is set to use CUDA for processing), and a couple of DeckLink Mini cards.

Same here, same specs.