Continous Perfomance Testing

[kzys]

We don't have a mechanism to catch performance regressions (such as #198).

We use BuildKite to test all PRs are correct, but we optimize its configuration for Frugality. We run multiple tests in parallel which allows us to use a single bare-metal instance to run all tests, but the performance numbers we can get from there would be fluctuating, based on other builds running on the same time.