Instructions
Select the "Settings" option from the "Call of Duty: Modern Warfare" main menu. This will load the utility that allows you to adjust aspects of the game's performance.
Select "Resolution." The game's currently selected resolution will be highlighted on screen. To increase the frames per second rate during a game of "Call of Duty," select a lower resolution from the list. For example, if the highlighted resolution is "1600x1200," select either "1280x1024" or "1024x768."
Choose the "Effects" option from the game's "Settings" menu. Disable any special graphical effects that are currently enabled, like "Shadows" and "Smoke Edges." These graphical effects may make the game look more realistic, but they require additional computer power to properly render. This lowers the frame rate of the game on slower computers. Disabling these options will increase the frame rate.