GitLab

* slow tests should be slow

* exception note

* style

* integrate LysandreJik's notes with some expansions

* Apply suggestions from code review
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* another slow test

* fix link, and prose

* clarify.

* note from Sam

* typo
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>