Core Web Vitals (LCP, INP, CLS)
LCP, INP and CLS, in both lab and field-like conditions.
Performance & load
We measure how fast the page opens and how many concurrent users it takes before things break.
Core Web Vitals measurements, slow-connection scenarios and staged load tests with k6. The output isn't just a score: we point at the query, the request or the asset creating the bottleneck.
From the checklist
31 check items
Staged load and soak tests
Concurrency is raised step by step until we find where it breaks.
3G / high-latency scenarios
Whether the flow can still be completed on a constrained connection.
Bottleneck analysis
Which query, which request, which asset — an address, not a score.
How we run it
- We agree the target figures for the critical pages and flows with you first.
- Core Web Vitals are measured in the lab and under constrained-connection scenarios.
- With k6 we raise concurrency step by step until we find the breaking point.
- Every slowdown is traced separately across network, server and client, then given an address.
What you get
- Per-page LCP, INP and CLS measurements against the agreed target
- Load test charts: response time, error rate and breaking point
- A bottleneck list — which query, which request, which asset
Out of scope
- Infrastructure scaling and server configuration are out of scope; we say what to do, we do not do it.
- Database query optimisation is recommended, not written.
What this typically turns up
- The category list takes 6.2 seconds with 1,400 products
- The checkout endpoint times out at 400 concurrent users
- Homepage images ship without dimensions and produce 0.3 CLS
Questions about this service
Do you run load tests against production?
No. Load testing happens only on staging or a separate environment; in production we take measurements only.
How far do you push concurrency?
To twice your target, or until the system breaks — whichever comes first. You set the target when you choose your criteria.
Are the results repeatable?
Yes. The k6 scripts ship with the report so you can run the same test yourself.
Included in
ReleaseWhole product, 3 platforms, pre-launchFleetRegression every release, monthlyEnterpriseRegulated sectors, custom SLA
Other services
Functional testingDo the critical flows work end to endRegression testingDid the new release break the old oneCompatibility matrixReal device and browser matrixSecurity reviewApplication review on the OWASP Top 10API testingSchema, error codes and boundariesPayment testingPayments, refunds and subscriptions with real cardsAccessibilityWCAG 2.2 AA and screen readersUsability reviewFlows that work but wear people downLocalization testingCountry by country, with native speakers
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