Lower Than Expected Framerates with RTX 4090

Recently upgraded to an RTX 4090 and booted up Nightingale again. In the Sylvan's Cradle Vault area, I am getting around 48fps on average. I have an RTX 4090 card which should be more than enough to handle this. Have all the setting on Ultra Quality and irresolution set to 4k. Is this a normal framerate for this game? Seem like I should be getting well over this amount with that card.

As an alternative, I can set AC Valhalla to max everything out and scale the resolution up 50% from 4K and still get 80-90 FPS.