Hey @VitalyFedyunin @albanD , do you know what could cause the seemingly sequential execution?
I tried the script on my laptop and saw the same behavior. When I increase the # of iterations from 2000 to 20000, it becomes even worse.
1 process
Time taken:  72.73709082603455
2 processes
Time taken:  229.3490858078003
Below is the CPU utilization graph. Looks like one process occupies half of the cores, and 2 process uses all of them. But still 2 processes execution time is worse than sequential.

Screen Shot 2020-02-25 at 11.58.09 AM706×1458 69.4 KB