I Downloaded it myself and have about 5-10fps in the main menu on a RTX3090 64GB , 3950X. Most of the reviews say the same. Colossal Order are suggesting you should play on very low detail. I was a massive fan of the original having played Sim City since 1993 but I cant even get into this. It shouldnt have been released so early IMO
It's not running great but also not terrible on my rig (3070ti, 12700K, everything on high). I've heard that the FPS in the menu is somehow worse than in game.
Gonna stick with my unfinished CS1 city for now since I am playing highly modded and aiming for a beautyfull city rather than actually playing the game..