Mobo: Gigabyte AB350 Gaming 3 BIOS Ver. F40
CPU: Ryzen 5 1600
GPU: "Asrock" Radeon RX 5700 XT Reference card
Memory: 16 GB DDR4 3000 CL15
No matter if I use V-Sync or not, Spotify cuts about 10 FPS on average from Forza Horizon 4. I set the game to Ultra, and then maxed everything else as well, essentially having an "Extreme" preset.
Without spotify playing music in the background, I have everything between 90-120 FPS while driving. After I turn on Spotify my framerate drops to about 75-110 FPS. I figured what if I limit my framerate with V-Sync so that I free up extra utilization on my GPU in case delivering Audio through Displayport is for some reason demanding on the GPU Core, I have power to spare. So I turned on V-Sync, stable 60 FPS, and then when I turn on some music in Spotify, my FPS drops to 52 stable.
My guess on why this is happening, is because of RDNA being new and not everything being tested quite yet, since I had an RX 460 4GB before and this did not happen, at least not that I can remember.
Will update the post with more numbers once I try other games tomorrow with Spotify on/off.