Just curious, what is your CPU setup… must be powerful or do you have several going at once?
It’s just a bog standard i7 machine, with 8GB of memory. I’ve spent out on the power supply (850W) and the graphics cards (about £750 combined), but they are not used by carrara.
The “secret” if you like is to kit bash and remove anything not seen. Most of the commercial models (which are wonderful and I’m grateful for them - even if my bank bal has suffered), are not built for combining into big scenes - so you have to strip bits out.
Then I made my own figures which I describe in detail in my tutorials - that’s a life saver for those large populated scenes.