I am running vellum simulations on Threadripper 16 core and AMD R9 390 and I can't get vellum to use more than 9 percent CPU and 9 Percent GPU. Is there a way to either throw it to one or the other? What is the bottleneck?

more important than the percentage, is how many core are you really using

the sim you have might not be hard enough for the power of the cpu.

can also mean the distribution of points to solve is not needing additional compute power, example

if you have 32 core, and you only have 10 points, maybe those 10 points can be solve with just one cpu.