When an inmovie game plays it is slow and regularly stutters....
Browse to the installation directory (C:\program files\Firaxis games\Sid Meier's Civilization 4 by default)
Double click on the file named _Civ4Config
Browse through the file for the line:
HideMovieBackground = 0
Change the 0 to a 1
If the problem persists then lower resolution versions of the movie are available from the links below:
Please refer to the readme.txt files in each of the download for installation instructions.