the huge load of 3d trees is a massive downer for, runs slow on my i7 and 2060rtx. can you do a version with 2d trees? there has never been any need to use 3d trees in AC.
You can delete the trees folder from Montjuich1975/extension to get rid of them. But there's only 500 or so. Runs fine for me on a similar PC to you and overall the track is still less polygons than a Kunos track. Hopefully it solves the problem for you