It's true GDPR is so broad you don't need to gather consent for such metrics, as it should be covered by contractual obligations (providing a best-effort servic

It's true GDPR is so broad you don't need to gather consent for such metrics, as it should be covered by contractual obligations (providing a best-effort service) and the legitimate interest of the operator (improving their service), both of which are exemptions to explicit consent. However, if you want good performance, do actual UX/performance studies without treating your users like lab rats (hell, even poor rats don't deserve that). Just nitpicking, but "first-party tracking" really falls into "phoning home" (just a different "home").