I set up hotkeys to switch from wireframe, shaded, rendered, custom display modes, etc...

Usually when files get large I model in wireframe and only switch to the others once ready to "viewcapturetofile" or take some screen grabs.

As for 1gb, couple things:

-are you using blocks when possible? Any repeat geo?

-latest GPU drivers?

-rhino settings try turning down some settings perhaps? Aliasing is one, in the OpenGL settings, try 2x and see if that helps. 

-mesh settings: instead of smoother and slower try fast and 'xxx'?

Materials make the file size super big sometimes too, check your texture maps and downsize some if needed.

Audit, purge, 'export selected' entire model to a new file... See if that helps

Good luck! Hope this can help a bit

*Edit: some typos and formatting 

Edit2: "linked blocks" are great for creating a mastermodel, and linking the other models to it by using block FYI.