I think we have different meaning of "fine"
I've got AC so i thought i'll do few benches with my vega 56 pulse which was left at stock, and i had 580x pulse as well, left at stock settings as vega. My cpu is oc'ed to 3.7ghz, i ran my ramm at 3200mhz and 2133mhz to see what difference that makes. AMD drivers 20.12.1.
AC VERSION: 1.16.4 (x64)
POINTS: 12653
FPS: AVG=86 MIN=16 MAX=98 VARIANCE=1 CPU=47%
LOADING TIME: 36s
GPU: Radeon RX Vega (3840x2160)
OS-Version: 6.2.9200 () 0x300-0x1
CPU CORES: 16
FULLSCREEN: ON
AA:2X AF:8X SHDW:2048 BLUR:0
WORLD DETAIL: 5 SMOKE:3
PP: QLT:4 HDR:1 FXAA:1 GLR:4 DOF:4 RAYS:1 HEAT:1
Same settings as above were used in all benches.
FPS: AVG=167 MIN=80 MAX=211 VARIANCE=8 CPU=89%
GPU: Radeon RX Vega (1920x1080)
FPS: AVG=62 MIN=5 MAX=190 VARIANCE=8 CPU=33%
GPU: Radeon RX 580 Series (3840x2160)
FPS: AVG=141 MIN=22 MAX=187 VARIANCE=3 CPU=74%
GPU: Radeon RX 580 Series (1920x1080)
580x with ramm at 2133mhz
FPS: AVG=55 MIN=15 MAX=69 VARIANCE=2 CPU=40%
GPU: Radeon RX 580 Series (3840x2160)
FPS: AVG=125 MIN=28 MAX=163 VARIANCE=7 CPU=89%
GPU: Radeon RX 580 Series (1920x1080)