Unfortunately, John’s reply above is probably fairly appropriate. Still, there ARE some things you can do to REALLY get close to your stated goals.
RHINO is one of the MOST capable tools on the market. If you SUCCESSFULLY achieve your intents using RHINO, you’ll have achieved a system that will perform capably, as you bring other tools into your arsenal. I also use AutoCAD (YES - ACAD ! ), Inventor, Cinema-4D and 3DS-Max.
1.Processor- YES multi-core XEON processors is appropriate, but let’s pause for a moment and touch on MAIN Processor cores. This way you can know how they best fit in, and THEN where to go from there. First, let’s remember that most CAD Software systems are still single-threaded. There may be some exceptions, but those will be limited to specific implementations so really don’t affect our conversation very much here.
Being a single-threaded system, RHINO will make effective use of ONE core, with HYPER-THREADING (Intel-Core processors) largely a non-factor, claims to the opposite notwithstanding. SO you’ve noticed what “seems” to be a bottleneck. Yes, you’re right. SO- get as FAST a multi-core XEON as you possibly can. Overclocked STABLE systems from such manufacturers as those offered by BOXX technologies,@xi and the i-x2 workstations from Mediaworkstations are great examples. They even offer MULTI-core options in both the XEON and intel-Core worlds that are truly astounding ! Lots of cores available, running REALLY fast. Current upper limits run around 3.4-4.0 Ghz, with some base speeds as much as 4.0 and with overclocking, if you’re careful to go with a fully tested and certified unit, follow cooling and related recommendations, your chosen vendor can help you optimize a result as close to your desired goals as can be currently achieved.
Ok, so RHINO is primarily single-threaded. Multi cores ? Yes, but for other reasons I’ll get to shortly.
2.RAM- Get AS MUCH RAM as you can achieve, based on the limitations of your chosen platform. High speed RAM - LOTS of CERTIFIED DDR-4 RAM at the highest bus speeds your platform (as recommended by your chosen vendor) will handle is the ticket. Remember, though, as you work with your vendor - let them know your application (not software) and discuss reasonable ways you plan to grow your toolkit. RAM above certain levels may be of little value. We see 32Gb typical in some standalone workstations, so that’s a reasonable starting point, but if you plan on doing more than basic 3D CAD, you can reasonably consider more, depending on additional services you’d be running at the same time (like rendering and animating, etc.) . More on that when I get to VIDEO. Work with your vendor. Their recommendations will be very important.
3. PRIMARY and WORKING storage- With available capacities, PCIE-SSD is the only viable option. Yes there are hi-speed physical drives out there and some REALLY COOL RAID options available, but you identified a system-lag problem, and the HD bottleneck is actually a probable culprit. LOTS of RAM will reduce file swapping but a hi-capacity PCIE-SSD is the answer.
4. Video- Work with your vendor on this, but you’ll find your most value in a video solution for RHINO that optimizes open-gl implementation. NVIDEA and AMD offer worthy solutions. While you’ll probably want to avoid a “Gaming” card, I’ve found RHINO’s use of NVIDEA’s implementation in their gaming cards to be a very viable smaller-scale approach. HOWEVER - and this is key - you’ll want to focus on one of those 2 (NVIDEA or AMD) in a Workstation class video implementation. Even so, however, more than 2 video cards in tandem (whatever your chosen protocol) is probably as much as you’ll get any value out of.
With that said. Boxx industries offers a render-station that piggy-backs onto your primary workstations, with PLENTY of capacity to expand beyond the 2 you have in your primary workstation. This will ACHIEVE your intent of having top-resolution running in real-time on one monitor while you’re designing on another. Real-time render solutions really shine, and RHINO’s implementation is among the BEST I’ve seen. While that uses multi (like “CUDA” ) cores on the GPU (Video card), for FULL rendering, you’ll need MAIN PROCESSOR speed and cores. You don’t need the external render-box to do this, but its a really sweet option when you’re looking at hi-end time and sunlight renderings, and the various animations you’ll be doing for concept presentation. ONE hi-dollar contract will make your purchase well worth it.
This is where the multi-core main processor can really shine. Hi-end renderers mainly use the “other” available cores on your main processor, so some processors with 12, 16, and 24+ are not unreasonable - with this excerpted from an on-line ad:
44 Core Xeon™ Workstation
Dual Xeon™ E5-V4 CPUs - 8-44 Cores, Up to 512GB, Low Price High Quality
If the cores are in your primary unit, that works, if they’re in your render-box, that works, and if you opt to network unused-available cores in other units in your office that works, too. I’ve successfully avoided “cloud” services, as ALL of my clients’ products are very proprietary, and NO, promises of "secure site … " really don’t impress me.
So- without making any “specific” recommendations ( read "endorsements 
) I think you can see that with a little pointing in the right direction, you CAN get there from here !
Final point - while you’re researching all of this, be sure to read everything you can that’s offered by the folks here at RHINO. They have some good starting points well worth considering. I’ve not found a SINGLE instance where a recommendation for my RHINO faulted at my other tools (Inventor … etc.). Their Technical support team is among the best I’ve dealt with in my 35 years as a Product and Equipment Designer for the Offshore Oil and Gas industry. I’m a 10-plus year RHINO user in Mechanical Design, Modeling and Animation, and find it to be a VALUABLE tool in my arsenal !
Post back with results ?
Thanks - and good luck !
-C.