No
Rhino is not a “multi-threaded” application. It does split off a few minor processes to other cores but nothing major. That’s because modeling is a serial process. Modeling has to be done ‘in order’. Consider the example of a box with filleted edges in a shaded display. The render mesh needed for the shaded display can’t be generated until after the edges of the box are filleted, and the fillets themselves can’t be made until after the box itself is created. First the box is made, then the edges are filleted, then the render mesh mesh created. You can’t put the box creation in one thread, the filleting in a second, and the mesh generation in a third and run all three processes at the same time.
Some tasks in computer work can be multi-threaded. Rendering is a good example. Since an array of pixels are being generated into an image, the image can be broken into 4 quadrants, and each processor can work on one quadrant independently.