I also get this issue. FPS starts at around 45-70 fps in 2d cockpit when first opening, then an 30 minutes or so later it is around 30. Exterior gets around 30 when first opening, but goes down to 19 ect. 3d Interior also gets similar performance as exterior, but just a tad higher. Sometimes when I first open the C400 fps are 19, but putting my computer in sleep and then re opening it puts the fps back to normal. My system is a MacBook Pro with 2.5 GHz 512 mb Nvidia Geforce 8600M GT if that helps you guys any. Hope this gets resolved soon!