In regards to performance, it now has the option to limit the number of guests in the park so reducing this number should help performance on lower PC's. I just played the Alpine map and this was defently a larger map. What Frontier may of done is have different size park sizes from small to large, The only way to work this out is get the same object and repeat it x number of times until you run out of room and do this on all of the maps and it will give you the smallest to the largest.