Lab is one run
Lighthouse is useful for debugging, but one synthetic navigation cannot represent every customer.
Run one protected mobile Lighthouse test. See lab metrics, available real-user Core Web Vitals, large images, blocking work, layout shifts, third parties, slow resources, and evidence-based fixes.
Use a public store, product, collection or landing-page URL.
The test uses a clean, throttled profile. It does not access Shopify Admin, private themes or customer sessions, and it never treats lab TBT as field INP.
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Measure before guessing
A single score cannot explain a slow storefront. The report keeps the lab run, eligible real-user data, resource evidence and Shopify guidance distinct.
One protected mobile run with the engine and profile shown.
Performance score, FCP, Speed Index, LCP, TBT and CLS.
Separate CrUX phone Core Web Vitals when publicly available.
Large files, sizing and LCP discovery opportunities.
Render-blocking resources and expensive JavaScript evidence.
Measured external transfer and main-thread work, without blame.
Read the result honestly
Lighthouse is useful for debugging, but one synthetic navigation cannot represent every customer.
CrUX uses aggregated real visits and may be unavailable or scoped to the whole origin.
An external script can add measured work without proving that an installed app caused the slowdown.