Instructions
Update your drivers, particularly your video card drivers. New drivers offer improved performance and are available for free on the manufacturer's website.
Reboot your computer. This ensures all unnecessary programs are turned off before you play, freeing up more resources for "Flight Simulator X." Additionally, disable your virus scanner before playing, making sure to turn it back on when you are finished.
Open the file FSX.cfg in Notepad. This file is located in the "Flight Simulator X" directory on your hard drive. Change the texture bandwidth line to read "TEXTURE_BANDWIDTH_MULT=400."
Download user-made replacement textures, such as those for trees and clouds. These textures are designed to speed up the FPS by providing less detail on objects.
Turn down the graphical settings in the "Options" menu. Settings such as the "Global Texture Resolution" can be set to "Low," and Light Bloom and Advanced Animations can be turned off. Experiment with the different settings to see which ones cause the biggest FPS gain on your computer.
Upgrade your computer's components. Replacing your CPU or video card with a newer model can result in FPS gains in older games such as "Flight Simulator X."