Instructions
Close any background programs. Music players, such as iTunes, can look innocent enough, but they take up some of the system's resources, and you need all the space you can get. If your computer does not have enough power to generate the simulated weather effects, you may suffer from a string of graphical failures and glitches.
Turn down the graphics settings in your game through the settings menu. You can reduce the strain on your computer by eliminating some features, such as real-time shadows. While some of these features can look great, they also take up a considerable amount of your system's resources. Lower unnecessary graphical effects to improve the efficiency at which your computer can run the game with the REX add-on.
Reduce the settings on the traffic. You can alter the settings for the air traffic by lowering the number of airplanes in the air and on the ground. You can also change the settings for the boat traffic and automobile traffic. The more activity that is going on in the game, the slower the game will run.
Reinstall REX and "Flight Simulator X." Game files can become corrupted for a variety of reasons or even be installed incorrectly. If this occurs, the game will still start like normal, but you can experience a range of graphical glitches.