How to work on performance issues
@zj mentioned that it would be good to have training for this.
@yorickpeterse has already written some great docs, such as https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/performance.md, but I wonder if having something that talks about the following things would be useful:
- DB seeds to slow down your development environment https://gitlab.com/gitlab-org/gitlab-ce/snippets/33946.
- The use of the request profiling feature, including how to get a production profile for a page.
- Using the staging database to test queries.
This could be a step-by-step approach to a single issue, or multiple approaches for different issues.