Set the Elegant.Ui.FormFrameSkinner.AllowGlass property to false.

Because of static nature of visual themes, you cannot set a theme in the Visual Studio form designer. However you can do this programmatically using only one line of code.

[C#]
SkinManager.LoadEmbeddedTheme(EmbeddedTheme.Office2007Black /* or any other theme */);

[VB.NET]
SkinManager.LoadEmbeddedTheme(EmbeddedTheme.Office2007Black)

You can paste it wherever you want, for example, in the main form's constructor.

When the application starts, it is compiled into the intermediate language (MSIL) and this comprises a good part of the startup time. So you can use the NGen tool, which ships with the.NET Framework, to compile the Elegant Ribbon assemblies it to native code. If you put the resulted assemblies into GAC, that will increase the startup speed even more.