Thank you Slasher. i have a 2 year old laptop.2.3 Ghz Intel CoreiS,Intel HD Graphics 3000 384 MB, 4 GB 1333 Mhz DDR3, OSX 10.8.5. i know the computer is low end as far as the minimum required is 512 as per Ben's reply. i have no trouble with the average ,detail airports.i always have the rendering at the low or default settings, so i guess with the computer I have ,I will have to be content with what it can handle. Thanks for your feedback. Gordon