A technical analysis of the graphics rendering in Cities: Skylines 2 has identified the reason why the performance is just so poor. Put simply, the game is trying to draw the cityscapes using a shocking number of polygons, with few systems in place to reduce the amount when it's not needed. It's not something that should be happening in a modern game but the recent breakdown also suggests changes within Unity are partly to blame, too.
Before the game even came out, developer Colossal Order issued a warning to potential customers that the performance of Cities: Skylines 2 had "not achieved the benchmark we targeted."
