This could be a pointer for devs. I seriously start to believe all these lags that got worse are due to the collision detection algorithms. Not to say there have been updates on paths and collision.
Take a late game with a huge amount of carts. Game starts to be unplayable for me. Collisions are massive with trade carts as they keep running into each other.
Maybe the devs know very well what cause the lag, but due to a lack of communication, allow me to share this hint anyway.