I've just finished the creation of the new Widget "StaticLabel". It utilizes the also new method in TextureCreator createTexture( String, Color3f, Font, int ), which creates a new Texture with a String drawn on it ('\n' again wraps a line).
This way a Label isn't assembled of many, many small rectagles, but only one Quad. This is much faster except when you change the text content very often.
StaticLabel extends Label and therefore supports everything Label supports. So you can switch to StaticLabel in place where needed.