Chrome has shipped experimental versions of all three Core Web Vitals that count soft navigations, and SPA-heavy sites see dramatic score gains. Among Android origins with 75% to 100% soft navigations, the share with good LCP (Largest Contentful Paint, the loading-speed metric) rises from 26% on the stable metric to 87% on the experimental one. The release landed October 13 in BigQuery, the CrUX API and the History API, and CrUX Vis now includes a toggle to display the new figures.

What does the release change?

Three new fields have been added to the Chrome User Experience Report (CrUX), Google's dataset of real-world Chrome performance: experimental_largest_contentful_paint_with_softnavs, plus one each for INP (Interaction to Next Paint, the responsiveness metric) and CLS (Cumulative Layout Shift, the visual-stability metric). They track the same measurements as the stable fields but count both hard loads and detected soft navigation events — the in-app page changes a single-page application makes without a full reload.

The mechanism matters. Previously, CrUX only measured an SPA's first load. Every subsequent in-app change was grouped with that first load, and all interactions and layout shifts were attributed back to the landing URL. Now, when a user action produces both a visible URL change and a visible paint, Chrome tracks it individually under the destination URL, subject to normal eligibility criteria. The data comes from the Soft Navigations API, on by default since Chrome 151 shipped July 28.

Which sites will see a difference?

Most will not. Between 66% and 75% of CrUX origins have fewer than 5% of page views via soft navigation, depending on platform. Only 7.0% on Android and 10.6% on desktop exceed 50%. Among the top 1,000 sites the picture flips: 35% on Android and 42% on desktop rely on soft navigations for more than half of page views.

Annie Sullivan, who wrote Google's announcement, put it plainly:

"If your site doesn't use JavaScript to dynamically swap out page content and update the URL without a full browser reload, you shouldn't expect to see any changes in your metrics."

Why do the scores improve?

For sites where more than half of page views are soft navigations, all three metrics improve. Sullivan explained the cause:

"This isn't because SPAs are faster than multi-page websites (MPAs) overall, but because follow-up clicks are faster on any site, bringing SPAs with many follow-up visits in line with MPAs with many follow-up visits."

INP improves because responsiveness is now measured per page view rather than by the slowest interaction across a session. Google says this roughly doubles Android pass rates for sites relying mainly on soft navigations. SPA-heavy sites still trail multi-page sites on INP, so heavy JavaScript during page changes remains a drag. CLS improves too, because layout shift events are grouped by view instead of session. Google states this puts SPA-heavy desktop sites on par with multi-page sites, with Android still slightly behind.

At the aggregate level, the September dataset release notes show 55.9% of origins passing Core Web Vitals without soft navigations counted, versus 59.5% with them counted.

What happens next?

Stable scores are unchanged. Chrome aims to conclude the metrics' experimental status in May 2027, subject to feedback, and says Search Console will adopt the new data once that happens. The November CrUX release is the next checkpoint, with soft-navigation versions of FCP (First Contentful Paint) and navigation types expected.

In the Web Vitals lifecycle, metrics move from experimental to pending for at least six months before becoming stable, so marketers watching SPA performance should compare both versions in CrUX Vis using the new "Include soft navigations" toggle — and interpret the numbers cautiously. Google advises readers to "expect some shifts from month to month as the measurement improves." Feedback runs through the web-vitals feedback group and the soft navigations spec repository on GitHub.