The Visual Effects dialog box has three options, “Let Windows choose what’s best for my computer,” “Adjust for best appearance,” and “Adjust for crappiest appearance best performance.” Some people have discovered the registry key where the Visual Effects dialog box remembers which radio button was most recently checked, but they found that when they programmatically manipulate the registry key, there is no effect on the actual visual settings. What’s going on? What’s going on is that the registry key is just there to tell you what you want to hear. It remembers which radio button you clicked, so that when you reopen the dialog box, the same radio button will be selected by default. The actual work of changing the setting happens when you click the OK or Apply button. The registry key is just for show. If you want to change a Visual Effects setting programmatically, you need to make the corresponding API call for that visual effect. For example, you might call System­Parameters­Info with the SPI_SET­NON­CLIENT­ANIMATION flag to programmatically enable or disable non-client animation.

Note of course that by doing this you are using a global solution to a local problem. The user’s visual effects preferences should be modified by the user, not by a program.