Investigate Artillery Performance

While working on #42 (closed) I noticed that Artillery was maxing out our runner's CPU when attempting to hit 100RPS. This was surprising as that's rate isn't extreme.

While researching this it was found that Artillery also only runs single core. It has experimental multicore support but this hasn't been updated in 3 years.

Currently we've had to employ running tests in parallel over multiple VMs. This isn't ideal as we want to have tests running on one place so they can collate all metrics and results in the end.

Task is to investigate this performance issue and explore possible solutions.