Discovered while investigating https://gitlab.com/gitlab-org/gitlab-ce/issues/25748
4x speedup locally by adding
.includes(:assignee, :labels, project: :namespace) to app/views/shared/milestones/_tabs.html.haml:24. Probably quite rare that someone has 300 issues in a milestone, but if they do then this will help.
8.15, 8.14, 8.13, 8.12
Exists after security fixes to 8.14, 8.13, but also on all 8.12 releases somehow. Possibly was fixed in 8.13 and then the security fix caused a regression.
Minor. Might be exacerbated by https://gitlab.com/gitlab-org/gitlab-ce/issues/25748, so more important for versions 8.13 onwards where the security fix was applied.