I am encountering performance issues while playing Sid Meier's Railroads.
If you are experiencing slowdown, try turning the detail levels for all graphical options down to the minimum, and then adjusting them one by one until you achieve an acceptable balance between visual quality and game performance. Note that turning down shader quality and tree density (in that order) has the greatest impact on the game's performance, so these options are a good place to start when tuning the visuals.
Graphics options can be accessed by selecting Options from the main menu and then Graphics. The lowest settings are as follows:
Full screen - Checked
Disable Clouds - Checked
Screen Resolution - 1024 x 768
Anti-Aliasing - None
Texture quality - Low
Tree density - Off
Shadow quality - Off
Shader quality - Low
NOTE: The "High" shader setting is for top-of-the-line cards only, such as the ATI X1800 or the GeForce 7900.