Most slow sites don't have one big problem. They have many small waits, stacked in the wrong order. On one production app I cut the JavaScript bundle by about half, and the biggest gains showed up exactly where they matter most: on low-end phones on ordinary mobile connections. This is the playbook I use to find and fix those waits in a Next.js site, organised around the three numbers Google actually measures. The three metrics, and what "good" means Metric What it me...