Graphics reps is what you are talking about. There are three parts to a model file, Regen data, 3D solid, and a section to store visual 3D graphic data. When you open a master rep the software regenerates the model and creates all the B-rep surfaces. It uses the most memory. The Geometry rep just loads the 3D model with no regen list, similar to an IGES file, its just a dumb solid but you can select surfaces and measure but not regenerate it, uses less ram than Master. This is stored in the model file too. Graphics rep is the graphic card display data. It has no dimensions or regen or vetor data, think of it as a 3D jpeg. You have to have graphics rep turned on in your config.pro file for it to work. Everyone in your design group needs to have these exact same config settings or you are wasting your time. (something PTC needs to implement- on the fly graphics rep)
save_model_display shading_lod or save_model_display shading_high
If you have it set to wireframe and open up a graphics rep when you shade you will see just wireframe, That being said if you change your config.pro to "shading_high" when you save your model the "shaded" graphics will be stored in the file but not displayed yet. Since the file is already open, you cannot change the display data for grahics rep while the file is open, (something PTC really needs to implement). There is a way but it takes a dozen mouse clicks while standing on a bowling ball with one foot. Easier just close the file and re-open it and you will see a shaded graphics rep. Ok, I wandered off some but this is important background.
So to test this, open up an assembly with a empty rep. Pick a part in the assembly, or subassembly and view-represent- graphics rep and the model will quickly appear shaded. No regen or 3D data will be loaded in RAM. Lets examine this, file -open and check the blue "in session" icon and no parts should be in session. If you change an assembly from master rep to graphics rep, then erase not displayed and all the parts will be removed from memory except assembly files which do not contain solid model data, you are now only using graphics card memory. You can open up huge assemblies in a minute with very little RAM usage. But, there is no geometry data, you cannot measure anything, its just a 3D jpeg on your screen but is great for routing pipes and cabeling so you wont visually route through a box.. Now the bad news, family tables parts do not store graphics data because they do not exist except in the generic. Something PTC needs to implement. All your pipe fittings and fasteners will disappear. Maybe there is a way but so far no one here has figured this out yet. You will find out that working in graphics reps can be very tricky, you are always one click away from loading the whole model and it takes allot of practice. I work with 10,000 parts in my model tree and only change to master rep the parts I am modifying. This keeps my RAM usage under 3 gig so things are still fast. Then convert them back to graphics rep and erase not displayed to recover memory. This should get you started and as you can see PTC really needs to look at implementing what I call "on the fly graphics rep creation" because it can be a nightmare setting 200 folks up with the right config options when no one will agree on shade_high, shade_low or wireframe setting. If you are in a release PDM system you will have to revise any part to get a graphics rep shade to work if it was released with wireframe setting. Good luck!
Teledyne Brown Engineering