I am working on " Spiral Galaxy Formation Simulation " example in Mathworks. I changed some numbers and equations (attached file).
I supposedly bought an expensive laptop so I could increase the number of particles. But I was surprised to see that even with high number of particles the CPU was at less than 20% in use, while none of the other stats was restraining the speed. The screen capture is indicating.
That seems to indicate you are only using one core.
First, I might check
Then you might take a read here: