Smaller downloads - map tiles and your company data now come compressed. Map tiles shrink to about a fifth, a big property list to a fortieth, so the map and every window load faster on a slow connection

Map cache - map areas you already visited stay on your disk more often instead of being downloaded again, also right after starting the game

Big companies - your property list and open windows refresh less often in the background, so deliveries and sales no longer keep your connection busy. The Properties tab stays live while it is open