pseudo geometry visualization using rhino SDK?

Hi GH people,

Is there any way to visualize geometries in Rhino without actually adding them in the current document?

One of my friend said that adding geometries to the document takes resources, and Rhino provides some ways to visualize geometries without adding them to the document. He said that, therefore, I better use those methods to visualize geometries in processing or visualize users' inputs during the plugin processing time. I was also told that I should actually add those geometries to the document only when the process is finished.

For example, when users type 'Box' command in Rhino, it instantly visualize a box in response to the mouse cursor, but it only displays geometries not adding them to the document yet. Likewise, Grasshopper visualizes geometries in processing with green color, but those geometries are not actual Rhino geometries in that they are yet to be added to the document. ( I am not sure if the word "actual" is the proper expression here...) It seems that, only when users 'bake' them, they are actually added to the document.

Please let me know how I can implement those pseudo geometry visualizations.

In advance, many thanks for help!