...
If the faster computer is used, the arrival rate of new jobs is λ. If the ten slower computers are used, each is responsible for 10% of the jobs arriving by a Poisson distribution at rate λ/10. Envision 10 separate queues leading to 10 separate slow computers. Each queue is "magically" assigned 10% of the customers. A job is never split and handled by multiple of the 10 computers in parallel.
...