I have two computers that are fairly different:
My "main" PC is getting a bit long in the tooth. It is a i7-6700k 4 core/8 thread @ 4Ghz. 32 GB ram, Geforce 1070 and 1TB NVME drive. Main issue here is CPU bottleneck. I generally only run a single group but in a pinch I can push that up to two groups. FPS varies widely depending on the zone, number of mobs, etc. With single group in GH prior I can hit fairly stable 60 FPS but that will dip as I move around. The March patch hurt my GPU performance and I haven't dug into the memory config to see if I can fix it.
My "big" PC is a AMD 3950x 16 core/32 thread. I think it runs around ~ 3.2 Ghz but that can change a lot based on load. It has 64 GB of ram and a GeForce 2070 GPU. This weekend I think I had 4x groups on it and it still had plenty of head room. This machine constantly outperform my "main" machine in terms of smooth game play. I don't have enough active accounts to find the limits of the machine.
Just fired up a single group. Depending on where I'm looking and what it has to render my FPS on the "big" machine is ranging from 57 FPS to 120 FPS. CPU isage ranges from ~ 15-30% of a core while in the background, up to ~80% when active.
However, that is with background rendering at 10 FPS ( recording raid ) and with models on. When I was pushing the limit of the box by using stick figures, hiding models, dropping clip planes, etc. I could get another ~ 15-30% clients.