What shifted
What kind of element moved in the captured layout shifts (heuristic, top-5 shifts per site).
At a glance the headline numbers for What shifted
What kind of element moved in the captured layout shifts (heuristic, top-5 shifts per site).
2.0% of captured layout shifts trace back to unsized media. Font swaps account for 6.0%.
The what shifted mix who uses what, and how fast each group loads
What shifted. On the fleet: 83.0% box grow, 8.4% displaced, 6.0% font text. 52.5% of sites use at least one box_grow.
Lowest-share bucket: LCP 1.4s. Highest-share bucket: LCP 1.6s. r = +0.30.
Passing LCP per bucket every category and count level at once - color is the pass rate
Each row is a category, each column its own count bucket (few on the left, many on the right); the cell is the share of those sites passing LCP.
Box grow swings the hardest: 85% of sites pass LCP with few, 76% with many. computed
Few vs many - does quantity cost LCP? the pass rate with few vs many of each category
Per category: the pass rate among pages with FEW of it (hollow ring) against pages with MANY (solid dot), worst trend first. Thin buckets are excluded from the endpoints.
More Box grow costs the most: the LCP pass rate falls from 85% with few to 76% with many. computed
Why this matters for the Core Web Vitals, and where to start fixing it
CLS tells you how much the page moved. This metric tells you what moved, and that decides the fix. An image without dimensions pushes everything below it down when it arrives. A swapped web font reflows whole paragraphs of text. An injected embed, banner or ad shoves the content aside after the page looked done.
Each element type has its own cure. Images need width and height so the browser reserves the box. Text needs a font-display strategy and a fallback font with matching metrics. Embeds and ads need a fixed slot that exists before they load. Identify the element first, then apply the matching fix.
How does this affect the Core Web Vitals?
Of the 5 categories, Embed grow separates passing sites from failing sites the most. Where Embed grow is rare: 86% pass the CLS. Where it is common: 55%.
Chrome field data from 94,910 sites, representing millions of real page loads. How we measured.