> the test is only concerned with the one page you are testing
A common practice is to use Lighthouse CI to test a set of representative pages across your site (such as your homepage, product search pages, and product detail pages if you're an e-commerce site). Every time that someone submits a pull request, Lighthouse CI runs Lighthouse against all of the representative pages to help you gain confidence that you have not introduced weird regressions on the rest of your site. https://web.dev/lighthouse-ci
> nearly everything it suggests you do will make that second page load slower
Which audits exactly are you referring to? To be frank, I highly doubt that claim.
A common practice is to use Lighthouse CI to test a set of representative pages across your site (such as your homepage, product search pages, and product detail pages if you're an e-commerce site). Every time that someone submits a pull request, Lighthouse CI runs Lighthouse against all of the representative pages to help you gain confidence that you have not introduced weird regressions on the rest of your site. https://web.dev/lighthouse-ci
> nearly everything it suggests you do will make that second page load slower
Which audits exactly are you referring to? To be frank, I highly doubt that claim.
Disclosure: I work on Lighthouse and web.dev