Core Web Vitals

reference · Scope: marketing-site · Status: current

Created 2026-06-11

Overview

Core Web Vitals (CWV) is Google's public, field-measured framework for evaluating user-perceived page experience. It comprises three metrics — Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS) — assessed at the 75th percentile of real-user (Chrome User Experience Report, "CrUX") data over a rolling 28-day window. The framework matters for two distinct reasons: it is a documented (small) Google ranking signal, and it is the empirical handle on loading, interactivity, and visual-stability problems that consistently correlate with bounce rate and conversion in independent and vendor-published case studies.

This page consolidates the canonical 2026 thresholds, the historical INP-replaces-FID transition, the catalogue of common metric "killers" with remediation patterns, the published revenue/bounce evidence (Walmart, BBC, Pinterest, Vodafone, Renault, Rakuten 24, redBus, Deloitte/Google, Economic Times, Akamai/SOASTA, Google neural-net), the platform pass-rate landscape as of November 2025, and a register of widely repeated statistics that fail primary-source scrutiny. See Research brief: Page Speed as a Moat — why CWV separates the agencies from the freelancers (piece 9 of 15) and Research brief: Website Performance & Revenue — defensible evidence for KW small-business owners (piece 17) for the full upstream research briefs from which this synthesis was drawn.

CWV thresholds (2026, confirmed unchanged)

Google's official "Good" Core Web Vitals thresholds remain unchanged through 2026:

Metric	Good (≤)	Needs Improvement	Poor (>)
Largest Contentful Paint (LCP)	2.5s	2.5–4.0s	4.0s
Interaction to Next Paint (INP)	200ms	200–500ms	500ms
Cumulative Layout Shift (CLS)	0.1	0.1–0.25	0.25

All measured at the 75th percentile of real-user field data (CrUX, 28-day rolling).

Source: https://developers.google.com/search/docs/appearance/core-web-vitals (last updated 2025-12-10 UTC); web.dev/articles/lcp; web.dev/articles/defining-core-web-vitals-thresholds. Confidence: Verified (primary Google documentation).

A site "passes" CWV only when all three metrics are in the Good band at p75 — a single poor metric fails the whole assessment for the page-experience signal.

INP replaced FID on March 12, 2024

Interaction to Next Paint became the responsiveness Core Web Vital on March 12, 2024, replacing First Input Delay (FID). FID measured only the delay of the first interaction; INP measures the latency of essentially every interaction across the page lifecycle and reports a near-worst-case value, which is materially harder to pass and far more diagnostic of real-world responsiveness problems. See INP officially replaced FID as a Core Web Vital on March 12, 2024 for the standalone reference.

Source: web.dev. Confidence: Verified.

INP 150ms target (200ms is the failing floor)

Internal performance budgets should be set above Google's "Good" thresholds, not at them. The Candid Creative build standard is:

LCP ≤ 2.0s (2.5s is the failing threshold, not the target)
INP ≤ 150ms (200ms is "Good", so aim 50ms inside)
CLS ≤ 0.05

Failing the build (or at minimum warning loudly) when Lighthouse-CI exceeds any of these on a representative page is the operating rule; see [[rule-enforce-performance-budgets-in-ci]].

Rationale: INP is the metric most local-market competitors are failing. Per the HTTP Archive 2025 Web Almanac: "In June 2025, 77% of pages achieved good Interaction to Next Paint (INP) scores" — meaning 23% still fail. For a Kitchener-Waterloo SMB-focused agency, INP is where the page-speed moat lives because most local agencies do not yet measure it. See Reference: the 8 most common INP killers — ranked by observed frequency.

Application: every new Astro/Next.js starter has Lighthouse-CI configured at these thresholds. Real-user monitoring via the web-vitals library reports INP at p75; an alert fires when a deployed page exceeds budget for three consecutive measurement windows.

CWV is a tiebreaker-class ranking factor, not a heavy lever

Independent studies consistently find CWV correlates with rank but is not a heavy weight.

Google's own framing (John Mueller, Search Central documentation): CWV is a "page-experience signal" that "contributes to" ranking — tiebreaker class.
Google Chromium research (cited via web.dev, Google News Initiative training): "When a site meets Core Web Vitals, research showed that people were 24% less likely to abandon the page."
Perficient (17-week study, June–September 2021, n=1,188 keywords across 6 industries): "The data confirms CWV scores are not a large ranking factor… It shows a general correlation between pages with higher CWV scores and rank, but the rollout of the Page Experience update did not change the shape or scope of that correlation to any noticeable degree." Confidence: high — independent, methodology disclosed.
Advanced Web Ranking (March 2022, n=3M pages, top 20 results): LCP showed the clearest visual trend with rank position 1-3 vs 8-10. But many top-10 pages had no CrUX data at all, meaning Google ranked them on other signals entirely.
Backlinko 208,085-page study (2021): no significant correlation between CLS and bounce rate, time on site, or pageviews. Useful skeptic check against vendor hype.

Bottom line: CWV is a real but small direct ranking factor. The conversion and UX gains are far larger and more defensible than the SEO gains.

Implication for client conversations: do not sell CWV as an SEO ranking lever. Sell it as a conversion / bounce-rate lever, where evidence is much stronger (Vodafone A/B test (2021): 31% LCP improvement → 8% more sales, 15% better lead-rate, 11% better cart-rate, [[rakuten24-cwv-conversion-33pct-2022]], [[deloitte-google-milliseconds-millions-2020]]).

CWV as AI-citation gate (2026)

The one direct analysis of Core Web Vitals as an input to AI-Overview / AI-search citation rates (Dan Taylor (SE Land, Jan 13 2026, n=107,352): CWV is a gate for AI citation, not a growth lever) found that CWV functions as a gate, not a positive signal: failing CWV reduces citation eligibility, but passing CWV does not confer a citation boost. This inverts the assumption marketers tend to make about "faster site = better AI Overview citation rate" (catalogued in the unverifiable-stats register below).

2026 performance budget for SMB sites

The applied performance budget for a small-business marketing site in 2026 is documented at Reference: 2026 performance budget — SMB marketing site (Candid default targets). Anchor numbers: total page weight ≤ 1.0 MB (versus the Web Almanac 2025 median of 2,559 KB on mobile); JS execution time ≤ 200ms on a Moto G Power; LCP image preloaded with fetchpriority="high" and served in WebP/AVIF.

Contractor-website CWV is load-bearing in the buyer journey

A contractor's own website CWV is a load-bearing trust signal. It is the second or third surface in the buyer journey (Multi-touch buyer journey for residential construction / major renovation: 4-touch sequence (discovery → validation → verification → contact); the contractor's own website is the 2nd or 3rd surface, not the 1st) — after discovery (referral, directory, ad) and before contact.

The structural reality ([[mobile-cwv-pass-rates-2025-and-3-second-abandonment]]):

48% of mobile sites pass CWV (mid-2025)
43.44% of WordPress mobile origins pass (June 2025; ~45–46% by late 2025)
Most contractor sites are WordPress + heavy page builders + shared hosting — they cluster on the fail side.
53% of mobile visits are abandoned if the site takes more than 3 seconds (Google/DoubleClick 2016, canonical).

Why this matters: a buyer who finds the contractor on HomeStars, then Google-searches the contractor's name on mobile, then clicks through to the site, abandons before LCP renders if the site is slow. The HomeStars lead is wasted at the contractor's own front door. Paying HomeStars roughly $7K/year to drive traffic to a site that cannot convert it is the structural failure mode.

How to apply:

In any contractor client audit, run PageSpeed Insights against the homepage and a representative deep page (a service page, a case-study page) on mobile. If LCP > 2.5s, INP > 200ms, or CLS > 0.1, CWV is the highest-priority technical work.
Diagnose the cause — typically heavy page-builder JavaScript (Elementor, Divi, WPBakery), unoptimized hero images, shared hosting with poor TTFB, or render-blocking third-party scripts. WordPress's primary failure mode is LCP and TTFB, not INP ([[mobile-cwv-pass-rates-2025-and-3-second-abandonment]]).
Treat CWV as a hard prerequisite before pitching content cadence or schema markup work. A fast site with okay content beats a slow site with great content for trust-signal purposes.
For new builds (Astro, Next.js, similar modern stacks): bake CWV testing into the build pipeline — the B&J marketing site is the worked example ([[client-bjf-build-performance-v2]]).
Caveat for any consumer-facing article: run a field sample of 25 Ontario GC websites before publishing the "60–70% likely to fail CWV" figure. The estimate is [Directional] until the audit happens.

LCP killers (catalogue)

Ranked by observed frequency in the field (HTTP Archive 2025 + practitioner consensus):

Hero image not preloaded and not given fetchpriority="high". Single largest cause. Google's own test on Google Flights: a single fetchpriority="high" moved LCP from 2.6s to 1.9s.
Lazy-loading the LCP image (loading="lazy" on the above-fold hero). Common WordPress default since 5.5; the CMS now excludes the first 3 images, but custom themes routinely undo this.
Slow TTFB — shared hosting with 800ms–1.5s server response; uncached dynamic queries; missing CDN.
Render-blocking CSS — Elementor stylesheets, theme.css from heavy themes.
LCP image hidden from the preload scanner (via data-src, JS lazy-load libraries, CSS background-image). Web Almanac 2025: 7% of sites still do this.
Unoptimised image format — JPEG/PNG instead of WebP/AVIF. WebP is 25–34% smaller than JPEG at equivalent SSIM ([[webp-25-34-smaller-than-jpeg-google-study]]).
Wrong-resolution images — no srcset/sizes, serving 4000px desktop heroes to mobile.
Third-party scripts blocking the main document while the LCP image waits in queue.

Remediation pattern: inline critical CSS → preload + fetchpriority="high" the hero → modern image formats → srcset/sizes → move TTFB-heavy work to edge / SSG / cache. See [[rule-preload-hero-image-with-fetchpriority]].

INP killers (catalogue)

The full INP-killers catalogue lives at Reference: the 8 most common INP killers — ranked by observed frequency. In brief: long tasks on the main thread from third-party tag managers, hydration cost on JS-framework sites, monolithic React/Vue islands that hydrate the entire page on first interaction, untransferred work that could run in requestIdleCallback, and synchronous input handlers that perform layout-thrashing DOM reads/writes. WordPress's INP pass rate is 85.9% — INP is not the typical WordPress failure mode; LCP and TTFB are.

CLS killers (catalogue)

Ranked by observed frequency:

Images and embeds without explicit width/height or aspect-ratio — the browser allocates wrong space, then reflows.
Web fonts with font-display: swap when the swap font has different metrics from the fallback (FOUT-induced shift). Web Almanac 2025: the median site uses 4 fonts; only 0.5% use the CLS-safe font-display: optional.
Late-loading ads, embeds, cookie banners that inject above-the-fold content.
App-injected banners on Shopify and similar (promo bars, free-shipping bars).
Dynamically-loaded above-the-fold content from JavaScript (consent managers, geo-personalisation).

Remediation pattern: reserve space with aspect-ratio or min-height → use font-display: optional with preload, or swap plus size-adjust metric overrides → place cookie banners outside the document flow (bottom-anchored fixed) → audit every plugin/app that can inject above-the-fold DOM.

Revenue and bounce evidence (the case-study cluster)

The published evidence linking page-performance changes to revenue, conversion, and bounce-rate movements spans more than a decade. The numbers below are quoted verbatim from the original sources; the confidence label on each indicates how cleanly performance is isolated from confounds.

Walmart (2012, foundational)

Devon Auerswald, Walmart Web Performance presentation, 2012:

"100 ms improvement = up to 1% incremental revenue; 1 s improvement = up to 2% increase in conversion."

Source: Walmart Web Performance presentation, 2012 (foundational; cited continuously across the performance community since). Confidence: Verified.

The first widely-disclosed e-commerce performance-revenue measurement at scale. The magnitudes (1% revenue per 100ms) became the default mental model in the industry, and have held up directionally across the Vodafone and Deloitte/Google replications.

BBC (web.dev, 2024)

"BBC lost an additional 10% of users for every additional second the site took to load."

Source: https://web.dev/learn/performance/why-speed-matters Confidence: Verified.

The cleanest "speed loss curve" stat in the public literature. The 10%-per-second loss is roughly linear over the relevant range (1–5 seconds), which makes it a useful rough calculator: if LCP is 4 seconds and the median is 2.5, roughly 15% of users are lost to that 1.5-second penalty.

Pinterest PWA rebuild (2017, foundational)

Pinterest's mobile-web rebuild as a Progressive Web App delivered 60% faster loads, +40% conversions, +40% time spent, and +44% ad revenue.

Source: Addy Osmani, "A Pinterest PWA Performance Case Study" (2017, foundational; results replicated in 2018–2025 case studies of similar mobile-web rebuilds). Confidence: Verified.

The strongest single-site evidence that mobile performance investment compounds into revenue at scale. Pinterest at the time had the engineering resources to instrument it cleanly. SMB scale will not see 44% ad-revenue lifts (no ad revenue), but the conversion-and-engagement direction generalizes.

Vodafone (2021)

See Vodafone A/B test (2021): 31% LCP improvement → 8% more sales, 15% better lead-rate, 11% better cart-rate. Vodafone's web team ran a true A/B test: a 31% LCP improvement produced an 8% lift in sales — one of the cleanest published performance-only attribution studies.

Renault (2021)

Renault analyzed 4 months of data across multi-million sessions. A 1-second LCP improvement was associated with -14 percentage points of bounce rate and +13% conversions.

Source: web.dev/case-studies/renault (2021). Methodology: linear regression on multi-month real-user data. Not a true A/B test; pre/post or regression-based. Confidence: Medium — performance correlation is well-isolated but not in an A/B sense.

Good for the "we make pages faster and conversions go up" general argument; not as airtight as Vodafone or Rakuten 24.

Rakuten 24 (2022)

Rakuten 24 (Japan) ran an A/B test in 2022 optimizing Core Web Vitals: CLS improved 92.7%, FID 7.95%, FCP 8.45%, TTFB 18.03%, and an ~0.4s LCP gain.

Outcome: +33.13% conversion rate, +53.37% revenue per visitor, -35.12% exit rate.

Source: web.dev/case-studies/rakuten (2022). Methodology: true A/B test — the only change between variants was performance. Confidence: High (performance is cleanly isolated).

One of the strongest "performance changes only" lift numbers in published literature. Pairs with Vodafone and redBus for a three-case A/B-test cluster.

redBus (2023)

redBus (India) optimized the date-change interaction on the search page, improving INP by ~72%. Outcome: +7% sales, with 6–7.2% CR uplift across operating countries.

Source: web.dev/case-studies/redbus-inp (2023). Methodology: RUM before/after on the key flow; not a true A/B, but performance was the isolated change. Confidence: Mostly yes — high attribution because the affected flow and code change are documented.

The cleanest published INP-specific lift number. Use when arguing for INP investment specifically, not generic "speed."

Deloitte / Google — "Milliseconds Make Millions" (2020)

Deloitte Ireland and Google measured 4 industry-wide site-speed metrics and found that a 0.1-second improvement correlated with:

+8.4% retail conversions
+9.2% average order value (retail)
+10.1% travel conversions

Source: "Milliseconds Make Millions" — Deloitte Ireland / Think with Google PDF, 2020 (foundational, still widely cited). Confidence: Verified (Deloitte primary).

The most-cited industry-wide study of site speed → revenue. Magnitudes are conservative (compared to individual-site studies like Vodafone, which show larger lifts), which makes it more credible as a baseline estimate for SMB conversations.

Caveat for SMB application: none of the foundational performance-revenue studies (Vodafone, Pinterest, Walmart, BBC, Deloitte) measured small-business marketing sites. Extrapolating to a Kitchener-Waterloo dental practice is plausible but unproven. Treat the magnitudes as directional indicators that the relationship exists, not precise predictions for any specific client.

The Economic Times (2021)

The Economic Times (India) brought LCP from 4.5s to 2.5s and CLS from 0.25 to 0.09 (passing all CWV thresholds). -43% bounce rate site-wide.

Source: web.dev/case-studies/economic-times-cwv (2021). Methodology: pre/post CrUX field data, AMP + non-AMP. Partial — not a true A/B. Confidence: Medium.

Companion case — Economic Times INP (2023): INP reduced ~4× via 30× TBT reduction + Next.js migration → -50% bounce, +43% pageviews on topic pages. Useful for the "INP investment pays off" argument specifically.

Akamai / SOASTA (2017, ~10B visits)

Akamai's 2017 State of Online Retail Performance analyzed approximately 10 billion user visits across top online retailers.

100ms delay → -2.4% desktop, -7.1% smartphone, -3.8% tablet conversions.
2-second delay → -36.5% desktop, -26.2% mobile, -25.1% tablet conversions.

Counterintuitive finding: desktop users were more conversion-sensitive, but mobile users were more bounce-sensitive — mobile users leave faster; desktop completers abandon further down the funnel.

Source: Akamai State of Online Retail Performance (ir.akamai.com / akamai.com newsroom). Confidence: High for the measurement; dated for application — cite as a historical retail e-commerce benchmark from 2017, not a universal current law. The widely repeated "1-second delay = 7% conversion loss" myth derives from this study and is misapplied to non-retail contexts (see the unverifiable-stats register below).

Google neural-net (Think with Google, 2018)

Google's neural-net analysis of 11 million mobile landing pages (Think with Google, 2018, 213 countries, 90% prediction accuracy):

Mobile load 1s → 3s: +32% bounce probability.
Mobile load 1s → 5s: +90% bounce probability.
Mobile load 1s → 10s: +123% bounce probability.

Confidence: High for the general curve, medium for exact numbers (baselines have shifted since 2018). Source: Think with Google, Mobile Page Speed Benchmarks, 2018.

The cleanest single non-vendor "bounce vs. load time" curve in the literature. Quote with the year so the audience knows it is directionally honest, not a 2026 number.

Mobile CWV pass rates 2025 and the 3-second abandonment threshold

Mobile CWV pass rates — the structural baseline

Per the HTTP Archive Web Almanac 2025 (using July 2025 CrUX):

48% of mobile sites pass all three Core Web Vitals (LCP, INP, CLS).
56% of desktop sites pass.
Year-over-year mobile pass rate: 36% (2023) → 44% (2024) → 48% (2025).

Source: almanac.httparchive.org/en/2025/performance. Confidence: Verified.

WordPress specifically

43.44% of WordPress mobile origins pass CWV as of June 2025 per the CrUX Technology Report (summarized by Search Engine Journal); updated late-2025 data has it at ~45–46% (HostingStep; Ben Ryan).
Failure mode is NOT INP (85.9% pass rate) but LCP and TTFB — only ~32% of WordPress sites have good TTFB, driven by shared hosting (CoreDash analysis; SEJ).

Confidence: Verified.

Page-experience weight in the December 2025 core update

Google's December 2025 core update increased the weight of page-experience signals beyond their previous tie-breaker role. Source: Ben Ryan / Search Engine Journal coverage. Confidence: Industry-consensus.

The 53% mobile-abandonment threshold — still canonical

The canonical source is Google/DoubleClick's "The Need for Mobile Speed" (September 2016, Think with Google):

n=3,700 aggregated Google Analytics samples, March 2016.
"53% of visits are abandoned if a mobile site takes longer than three seconds to load."

Sources: Think with Google; restated in Google AdSense Help. Confidence: Verified.

The 2016 study remains the single most-cited number on mobile abandonment because nothing comparably-sized has replaced it. Treat as Verified for the 3-second threshold; the underlying user behaviour has likely intensified, not weakened, in the intervening decade.

Zero-click reality

58% of Google searches result in zero clicks to external websites, per SparkToro research. WSI's 2025 AI-era visibility report restates:

"Zero-click searches now account for nearly 60% of Google activity, signalling a tectonic shift in how people engage with search results."

Sources: SparkToro; WSI 2025. Confidence: Verified.

Caveat — field-sample audit not yet conducted

A field sample of 25 Ontario GC websites is a research item Candid Creative should run before publishing a consumer-facing article. Placeholder estimate based on platform mix + CrUX baseline: 60–70% likely to fail CWV on mobile [Directional — derived from HTTP Archive 2025 WordPress pass rates, adjusted upward for builder-heavy construction vertical].

Web Almanac 2025 — mobile page weight (2,559 KB)

Median mobile home-page weight reached 2,559 KB in July 2025; desktop 2,862 KB. That is +7.8% YoY. Average mobile Total Blocking Time: 1,916 ms — almost 10× the 200ms best-practice target.

Source: HTTP Archive Web Almanac 2025 (Page Weight + Performance chapters); also cited via corewebvitals.io. Confidence: Verified.

The compounding-tax framing: the average page is getting heavier, not lighter. Every plugin update adds asset, every embed adds bytes, every "modernization" adds JS. The race is being lost across the average web; the moat for disciplined teams widens. A site that defends a 1.0 MB budget today is materially differentiated from the median 2.56 MB site, and the gap will be wider in 2027. See Reference: 2026 performance budget — SMB marketing site (Candid default targets) for the budget framework.

Web Almanac 2025 CWV pass rates

The Web Almanac 2025 CWV pass-rate data is referenced in summary above (48% mobile, 56% desktop, 77% of pages achieving good INP in June 2025); the full chapter analysis with per-metric breakdowns is preserved at Web Almanac 2025: 48% mobile / 56% desktop origins pass all 3 CWV; LCP is the bottleneck.

Platform CWV pass rates (November 2025 CrUX Tech Report)

Mobile CWV pass rate, all-three-thresholds, per the HTTP Archive CrUX Technology Report, summarized by Search Engine Journal December 2025:

CMS	Nov 2025	Jun 2025	YoY direction
Duda	84.87%	83.63%	up
Wix	74.86%	70.76%	up
Shopify	not in Nov SEJ breakout	75.22%	(relatively flat)
Squarespace	70.39%	67.66%	up
Drupal	63.27%	59.07%	up
Joomla	56.92%	–	up
WordPress	46.28%	43.44%	up but slowest gainer
Global (all origins)	~48%	~49%	(flat)

Trend (June 2024 → July 2025 → November 2025):

WordPress: 40% → 45% → 46.28%. Gain of ~+4 pp/year — half of Wix's +14 pp YoY and Duda's +11 pp YoY.
2025 Web Almanac quote (verbatim): "More extensible platforms improved less. WordPress and Drupal each gained around 4% year over year."

Confidence: Verified (CrUX is the authoritative public dataset; SEJ's SQL methodology is disclosed).

Reading the numbers correctly: a WordPress site is roughly 1.8× less likely to pass CWV than a Duda/Wix/Squarespace/Shopify site (mobile, November 2025). The closed-CMS lead is widening, not narrowing. See WordPress CWV gap causal decomposition (May 2026): ~40-50% hosting/TTFB, ~20-30% page builders, ~15-20% plugins, ~5-10% core, ~5-10% theme for why. Supersedes the earlier June 2025 numbers in [[platform-cwv-pass-rates-june-2025]] — both kept for historical comparison.

March 2026 LCP-tightening rumour (refuted)

Claim being refuted: Multiple SEO blogs (Digital Applied, MonsterMegs, IdeaFueled, ClickRank, Mewa Studio, w3era) claim Google tightened the LCP "Good" threshold from 2.5s to 2.0s with the March 2026 core update, citing a "Search Central blog post published March 18, 2026."

Refutation:

The cited Search Central blog post does not exist. Google's official documentation, last updated December 10, 2025, still states LCP ≤ 2.5s.
Search Engine Roundtable (Barry Schwartz, April 8, 2026): Google's only public communication about the March update was a Search Status Dashboard note. No threshold change announced.
Whitehat SEO and BuildMVPFast both state explicitly that thresholds have not changed.
The original Digital Applied post that started the rumour is the only source; everything else traces back to it.

Source: Google Search Central docs (current); Search Engine Roundtable April 2026; Whitehat SEO + BuildMVPFast confirmations. Confidence: Verified refutation.

Operational guidance: treat the 2.0s / INP-elevation claim as unconfirmed industry rumour until Google publishes otherwise. Use the 2026-confirmed thresholds table above as the actual reference. This is a textbook [[rule-cite-with-named-source-and-url]] case — the discipline of trying to find the cited Search Central post catches that it does not exist.

Unverifiable stats catalogue — speed/conversion claims Candid will not quote

The following statistics circulate widely but are not supported by primary evidence in 2026. Candid Creative does not quote them in sales conversations or marketing copy:

"A 1-second delay reduces conversions by 7% across all sites." Traces to Akamai/SOASTA 2017 retail data. Defensible as a retail e-commerce benchmark from 2017, not a universal law. For a KW lawyer or HVAC contractor, this specific elasticity has not been demonstrated.
"Amazon loses 1% revenue per 100ms of latency." Reportedly Amazon internal research circa 2006 (Greg Linden). No public methodology, ~20 years old, Amazon-scale operations.
"Core Web Vitals doubled in ranking importance" / "Google made CWV twice as important." Cited by some marketing blogs but not in any Google primary statement. Google has consistently described CWV as one of many page-experience signals, tiebreaker class. See the CWV-tiebreaker section above.
"53% of mobile users abandon in 3 seconds" applied to 2026 baselines. The original study (Google/DoubleClick/SOASTA, 2016) is nearly a decade old. Networks, devices, and tolerance baselines have shifted. Quote it as historical context, not a current 2026 number.
"Faster site = better AI Overview citation rate." No defensible primary research supports this as of May 2026. The one direct analysis (Dan Taylor (SE Land, Jan 13 2026, n=107,352): CWV is a gate for AI citation, not a growth lever) found the opposite of what an SEO marketer would assume.
Agency "case studies" claiming "redesign → +40% conversions" as performance wins. A redesign confounds content, layout, CTA copy, navigation, trust signals, and performance. Cannot attribute the lift to speed without an isolated A/B test. Reject these.
Conversion-rate elasticity for "professional services" specifically. No major isolated study (Deloitte, Akamai, web.dev cases, Portent, Contentsquare) breaks out elasticity for lawyers, accountants, dentists, or consultants in a defensible way. Extrapolate cautiously from Deloitte lead-gen and Portent B2B — but flag as "general B2B," not "professional services-specific."

Why this rule exists: sales conversations are won on credibility. A quoted statistic that does not survive scrutiny loses the room. See Research brief: Confidence Levels, Sources, and Dated Claims — why every statement on a credible site should be verifiable (piece 15 of 15) for the broader sourcing discipline.

Sources and confidence

Confidence labels appear inline above. The aggregate source map for this page:

Verified — primary Google documentation: developers.google.com/search/docs/appearance/core-web-vitals (2025-12-10); web.dev/articles/lcp; web.dev/articles/defining-core-web-vitals-thresholds; web.dev/learn/performance/why-speed-matters; web.dev/case-studies/* (Renault, Rakuten, redBus, Economic Times); Search Central documentation on page-experience signals.
Verified — primary industry research: HTTP Archive Web Almanac 2025 (Performance + Page Weight chapters); CrUX Technology Report; Walmart 2012 (Auerswald); Pinterest PWA case study (Addy Osmani, 2017); Deloitte Ireland / Think with Google "Milliseconds Make Millions" 2020; Google/DoubleClick "The Need for Mobile Speed" 2016; Think with Google Mobile Page Speed Benchmarks 2018; Akamai State of Online Retail Performance 2017.
Verified — independent ranking-factor studies: Perficient 17-week study (June–September 2021, n=1,188 keywords); Advanced Web Ranking March 2022 (n=3M pages); Backlinko 208,085-page study (2021).
Industry-consensus: Search Engine Journal December 2025 coverage of CrUX Tech Report and December 2025 core update; HostingStep and Ben Ryan late-2025 WordPress CWV updates; CoreDash WordPress TTFB analysis.
Verified refutation: Search Engine Roundtable April 8, 2026 (Barry Schwartz); Whitehat SEO and BuildMVPFast confirmations that the March 2026 LCP-tightening rumour is unsupported.
Single-source / Directional: Candid Creative's 60–70% Ontario-GC CWV-fail estimate (pending 25-site field audit); SparkToro / WSI 2025 zero-click figure (58% of Google searches).
Unverifiable / rejected: the seven claims in the unverifiable-stats catalogue above.

See Research brief: Page Speed as a Moat — why CWV separates the agencies from the freelancers (piece 9 of 15) and Research brief: Website Performance & Revenue — defensible evidence for KW small-business owners (piece 17) for the upstream research briefs that informed this synthesis.