The verdict in three sentences
For a staffing network where 72% of candidates arrive on mobile, a 450 ms INP is a direct brake on applications: every tap on "Apply" or on a job filter feels slow. A performance audit (EUR 1,500 to 4,000 ex VAT) is enough to know whether a targeted optimisation fixes the problem or whether a technical rebuild (EUR 15,000 to 35,000 ex VAT) is needed. The decision should rest on numbers, cost per application before and after, not on a Lighthouse score alone.
What Core Web Vitals really measure in 2026
Google assesses three metrics on field data (CrUX report, 75th percentile of real visits over 28 days). For a staffing site, these thresholds translate into very concrete behaviour: a candidate filtering "forklift driver Dublin 15" jobs on an entry-level Android phone feels every millisecond.
| Metric | "Good" threshold | "Poor" threshold | Typical ageing staffing site | Frequent cause |
|---|---|---|---|---|
| LCP (main content display) | under 2.5 s | over 4 s | 3.8 to 5.2 s on mobile 4G | Unoptimised hero image, slow CMS |
| INP (responsiveness) | under 200 ms | over 500 ms | 350 to 550 ms | Tracking scripts, chat widget, client-side job search |
| CLS (visual stability) | under 0.1 | over 0.25 | 0.15 to 0.30 | Cookie banner, ads, web fonts |
| TTFB (server time) | under 0.8 s | over 1.8 s | 1.2 to 2 s | Shared hosting, no caching |
| Job page weight | under 1.5 MB | over 4 MB | 3 to 6 MB | Libraries stacked over 8 years |
| Third-party scripts | fewer than 8 | more than 20 | 15 to 30 | Ad pixels, ATS, chat, A/B testing |
A 450 ms INP almost always comes from JavaScript: the job feed synced from the ATS, filtered in the browser, combined with 3 or 4 marketing tags loaded at start-up. That is the first thing to tackle.
Audit, targeted optimisation or rebuild: three costed scenarios
The figures below are 2026 market estimates for Dublin (agencies and independent studios), not Kolonell rates.
| Scenario | Budget ex VAT (market estimate) | Timeline | Expected INP gain | When to choose it |
|---|---|---|---|---|
| Performance audit only | EUR 1,500 to 4,000 | 1 to 2 weeks | None, it is a diagnosis | Always first |
| Targeted optimisation (images, cache, third-party scripts) | EUR 4,000 to 9,000 | 3 to 5 weeks | 450 ms to 250-300 ms | Recent CMS, low technical debt |
| Front-end rebuild (server rendering, rewritten job search) | EUR 15,000 to 25,000 | 8 to 12 weeks | 450 ms to 120-180 ms | Slow job search, outdated theme |
| Full rebuild with 14 branch pages | EUR 25,000 to 35,000 | 12 to 16 weeks | 450 ms to 100-150 ms | Site older than 6 years, weak local SEO |
| Monthly monitoring (CrUX tracking, alerts) | EUR 150 to 400 per month | ongoing | Prevents regressions | After any intervention |
A serious audit delivers a prioritised list: each fix with its estimated impact in milliseconds and its cost in days. If the audit shows that 70% of the problem comes from 3 third-party scripts and shared hosting, targeted optimisation is enough. If job search is a heavy client-side component, a front-end rebuild pays off.
Measuring the gain in applications and client enquiries
A technical rebuild is justified by its commercial effects. Instrument the site before the work, for at least 4 weeks, so you have a baseline.
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| Metric | Before (example) | Post-rebuild target | Measurement tool |
|---|---|---|---|
| Job view to application rate (mobile) | 2.1% | 2.8 to 3.2% | Analytics, "Apply" events |
| Application form abandonment | 58% | 40 to 45% | Form step tracking |
| Client staffing enquiries per month | 35 | 42 to 48 | CRM, B2B form |
| Share of URLs rated "good" | 18% | over 75% | Search Console |
| Organic clicks on branch pages | base 100 | 115 to 130 within 6 months | Search Console |
Studies published by Google and by job board publishers regularly report conversion increases of 10 to 25% when mobile INP drops below 200 ms. Use a cautious range in your business case and verify it on your own data.
Mini case study
Thomas, marketing director of a network of 14 staffing branches in Dublin (illustrative scenario), receives 6,000 online applications per month. His media acquisition spend is EUR 9,000 per month, or EUR 1.50 per application. The audit (EUR 3,000 ex VAT) recommends a front-end rebuild at EUR 22,000 ex VAT. Cautious assumption: +15% applications at constant media spend, so 900 more applications per month. At EUR 1.50 each, that is EUR 1,350 of monthly value, so the EUR 25,000 investment pays back in about 18 to 19 months, before counting additional client enquiries. If 5 extra B2B enquiries a month lead to 1 contract worth EUR 4,000 in margin, payback falls under 6 months.
FAQ
How long before the effect shows in Search Console? CrUX data covers a rolling 28 days, so allow 4 to 6 weeks after go-live. The "good" status appears URL group by URL group once 75% of visits are under the thresholds.
Does a Lighthouse score of 95 guarantee good Core Web Vitals? No, Lighthouse is a lab test on a single simulated visit. A site can score 95 in the lab and still have a 400 ms field INP because of real interactions on phones costing under EUR 200.
Should we remove the chat and ad pixels? Not necessarily, but they should load after interaction or through a deferred tag manager. That single change often saves 80 to 150 ms of INP.
Does our ATS integration force a rebuild? No, the job feed can stay powered by the ATS via API or XML feed. The rebuild changes rendering (server-generated pages refreshed every 15 to 30 minutes), not the data source.
What budget should we plan after the rebuild? Plan EUR 150 to 400 ex VAT per month for monitoring as a market estimate. Without checks, one new third-party script can push INP back up by 100 ms in a single release.
Let's scope your project. Send us your site URL and application volumes: we will scope the technical rebuild, an indicative budget and a timeline. Detailed quote within 48 h. WhatsApp +221 77 596 93 33 or request a quote.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
