I do not think your system is all that bad, and I wonder if adding more hardware power will solve the long waiting times.
Can you elaborate on the type of operations you do that will make you wait 45 minutes?
What it looks like from your images you have a very dense lettuce structure over a large surface. Is that the cause of the long waiting times? The rest of the geometry present seems to be not that complex.
What I’d suggest for a project like this, is to separate different parts of the design in separate files.
Use worksessions if you do not already :
For this project, I would at least separate out the canopy/roof structure. That makes it easy to work on the design of the floors and other functionalities with just a dummy surface present for the canopy/roof.
Note that the use of Blocks ( http://docs.mcneel.com/rhino/5/help/en-us/seealso/sak_blocksgroups.htm ) can reduce the filesize, and easy up the workflow very much.
Yet note that blocks are also known to cause a lag in display performance.
Another issue that still run into with complex projects is the desire to constantly see the design in all it’s detail. It’s tempting to always populate such roof structure with detailed geometry at every stage. Yet this has proven to me to cause too much of a distraction, as waiting times increase and my mind wanders of in all direction, but the one I was going to.
When focusing on global structure, use the simplest geometry possible ( be it single mesh faces, curves, points …) Use a global point of view to design the overall positioning and setup of the structure.
Use a local point of view and operate on just a small selection of the paneling points to setup various variations of more detailed structures.
Only occasionally create the complete structure in detail, and even then just for visualization and presentation and not as a working file. If needed save a copy and delete all structure higher up, keeping only the ones in close relation to the base structures.
Maybe I’m approaching you with advice that simplifies your needs and skills, if so don’t feel offended.
If you elaborate in more detail what specific issues you run into, the greater the chances someone over here can help in easing your workflow.