Truthfully, this is a valid question. Planet Coaster ran into a similar issue. While the game was optimized for multi-core support, that generation of the cobra engine ran on DirectX11 which has a single core limitation on some functionality which resulted in issues with PC.
Sorry, I didn't want to upset anyone, I'm probably not in a very good mood today.
When I download a big park from the workshop at planet coaster, the performance goes down. I would like to know if frontier learned from this and adjusted the planet zoo engine to support multicore cpu's in a better way.