There are two new options in the video setup screen of Aces high II 68D (press the "Video" button on the clipboard immediately after the clipboard stops moving). One option allows all the textures to be loaded to system ram, and the other is for loading all the textures to video ram.
If you have 256MB of video ram and set the maximum texture size to 256 or 512 (maybe), then exit the game and restart, the option for loading to video ram should be available.
If you have 512MB of system ram, or more, you should be able to use the option to load the textures to system ram.
It would not be wise to check both options.