Automated performance tests (beginning load --> render)

[hilvmason]

• We have this, understand how to utilise here
• Benchmarking over time
• Background loading times independent of UI specific loading

Relates to #6647

Note: For this to be useful, we need to make the environment and outputs more consistent

[danjm]

We might what to run this tests in a job that is independent of circleci runs triggered by commits. We could do this daily, and compare to averages over time.