GPUs have been general-purpose many-core processors for like fifteen years now. Please stop designing simulations that run exclusively on CPU… and especially stop tying your simulation speed to the goddamn renderer.
I’ve written a 60 Hz renderer for a game that’s allowed to chug while you glide smoothly through it, and I’ve written a 60 Hz physics engine for a game that gets fractional frames per second, and I’m just some schmuck. What is your excuse? What kind of NP-hard nightmare did you design for yourselves, instead of identifying bottlenecks and faking the hell out of them? SimCity could run on 8-bit microcomputers. You cannot possibly be struggling to reach an acceptable minimum complexity, using hardware that’s forty years newer and ten thousand times faster.