What is the current population limit you can enjoyably hit with the best hardware?

I last played about a year ago and I hit about 250k population when my 14900k couldn't keep up anymore. I didn't loose any FPS, it was still running smoothly just the sim speed was very slow, slower than 1x and I couldn't make it go faster. Is around 250k around the biggest city or has the game been optimized to go higher?