You've spent weeks tuning Magento 2. Redis is warm, Varnish is humming, your slow SQL is gone, and the storefront scores in the green. Then a two-line change to a tax observer ships on a Friday, and on Monday your TTFB is up 400ms and the checkout queue is backing up.
Source: [Dev.to](https://dev.to/magevanta/magento-2-performance-regression-testing-catch-slowdowns-in-ci-32h2)