Maybe it was during the initial "generating textures" phase when you first launch it, but it should definitely not be lagging at the menu.
I'm on a 2080 S + 9700k and the game runs pretty decently, small city and it averages maybe 45fps with most settings on high at 1440p, run over 70 fps if I turn down the settings a bit, but I like the graphics and I can live with lower FPS on a city builder game.
Yep, also Grizzly Research is a short seller, and this lawsuit was filed by an Arkansas attorney general. Arkansas makes really bad decisions like weakening child labor protection laws, don't trust anything that comes out of that state.