Honestly I don't know why people are making such a fuss, the game is clearly blottlenecked by something I bet it's CPU but I didn't read or test it enough to say for sure, still, seen people reporting performance on the 40s with GPUs much more powerful than mine while playing on low quality. in my case, the game defaulted to high quality and I didn't try to change it, on my RTX 3060 and it's still running at about 38fps, so it's probably CPU limited.
Thing is, it's a SIMULATION game! they have HISTORICALLY been CPU heavy and runs slow even though their graphics are also historically inferior to their contemporary, simulations are just very compute intensive imagine having ot simulate hundreds of thousands of people living their daily lives while displaying their current positions in real time in a fully 3D modeled and simulated city. I honestly find it's marvellous that it works at all.
Also, simulation games just dont need high FPS, it really doesn't matter if its running at 30 or 400fps, who cares? Yeah it stutters frequently but also, it's a simulation game, it's not like an enemy AI will kill me because the game hitched, I don't care!
That said, I'm only playing it because it's on gamepass, I wouldn't buy it, and I will not buy any DLC, because I don't want to justify Colossal Order's practices of releasing a hundred different super small DLCs, a lot of which are just a new radio station or a new building that you can put on your city and end up charging 6x the base game price when all of it is included. That's just a ty practice and I refuse to condone it.