[GuyFawkes]

The original ps1 used to have the same problems after each patch. I dont know exactly why, but it just seems the more you try to tweak settings, the game just doesn't like it.
My solutions has been to log out, delete the User Options file in your ps2 beta folder, then relaunch any time you change anything and especially after each patch. The game will relaunch with settings on medium by default. You can change this to low or high from then , exit and relaunch.
Other than that it may be down to AMD or even ram, but the game definately seems to run better the less you change settings. It's almost as though it works off default settings, then realises its not default for flora, has to recalculate to put that into the equation, then realises that render distance is higher, and recalculates again, ad nausium.

I think calculations per area need to be sorted out somehow to what you can actually see. You can see silly triangles through hillsides, drive to the other side of that hill and realise those triangles are in a tower behind a base behind that hill you just drove around. Your pc is calculating what they are doing, interacting with and making calculations for all those as well as anything else in between and within the same radius. Thats huge unnecessary load, made worse in busier areas.