Early CLS comes from load-time sizing and fonts; late CLS comes from dynamic injection, route changes, and interaction-heavy UI. Here is how to split the signal, reproduce cumulative layout shift after load in the lab, and fix what field data actually measures.
What a Google Lighthouse score means: scoring curves, Lighthouse 10 weights, good-score bands, and lab scoring vs PageSpeed Insights and CrUX.
PageSpeed Insights can show lab CLS and INP while field data is missing. Here is why CrUX omits metrics, how origin vs URL eligibility works, and what to do next.
You shipped a Core Web Vitals fix, lab scores look better, and Search Console still says Needs improvement. Here is how CrUX's 28-day rolling window works, when field data updates, and what to monitor while it catches up.
When LCP is red, start with TTFB, then clear the path to the LCP element, mark it fetchpriority="high", and defer non-critical JavaScript until after load. Four practical changes teams can ship this week.
FCP and TBT are not Core Web Vitals, but they show early paint time and main-thread blocking in Lighthouse runs. Here is what each measures, how they relate to LCP and INP, and when to add them to monitoring budgets.
CLS fails in the field for a small set of repeatable reasons: missing media dimensions, late fonts, ad and embed slots, and content injected above the fold. Here is how to read the signal, rank fixes, and stop regressions coming back.
What Interaction to Next Paint measures, why it replaced First Input Delay in March 2024, and how to treat INP in audits and ongoing monitoring.
Mobile and desktop Core Web Vitals can tell different stories. Here’s how to monitor both so your reports stay accurate and your fixes stay prioritised.
You've run PageSpeed Insights. The scores are poor. You've optimised images, minified CSS, and still LCP stays red. Or CLS keeps spiking on client sites. Or users complain that clicks feel sluggish even though the page "loads fast". The problem isn't always obvious—some of the worst PageSpeed mistakes look like best practice at first glance.
You need to know whether fixing Core Web Vitals will actually move the needle for rankings — and what to tell clients. Here's what the data shows so you can prioritise with confidence and justify monitoring.
Website load speed is how quickly your pages load and become usable for visitors. It’s the time from when someone opens a link to when the main content is visible and the page responds to taps or clic...
