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How to check and improve Shopify website speed

Measure the live storefront, identify the slow template, and test one change at a time.

Updated September 7, 2026 · Layzr

Start with a Layzr website audit to check the performance of an individual storefront URL. Use Shopify's web performance reports alongside it to understand real customer experience. A homepage score alone cannot tell you whether a product page or collection template is slow.

This walkthrough combines those two views into a repeatable test. Layzr includes one free audit for a new account; additional runs depend on your plan and credits. Keep a record of the URL, device, test date and change so you can tell whether an edit helped.

1. Find the affected metric in Shopify

In Shopify admin, open Online Store and look for the performance summary on the Themes page. You can also use Analytics → Reports to find the web performance reports. Access requires the Reports permission. These reports cover loading, responsiveness and visual stability using real visitor data.

  • LCP: the main content takes too long to appear. Investigate the largest visible image or text block and what delays it.
  • INP: interactions respond slowly. Reproduce the affected action, such as opening a menu, choosing a variant or adding to cart.
  • CLS: visible content moves after loading. Watch for a banner, image, font or app widget changing the layout.

Compare mobile and desktop separately. Note the date of a theme update or app install before attributing a change to it. Timing gives you a hypothesis to test, not proof that the app caused the slowdown.

2. Test the actual shopping journey

  1. Open the published storefront in a signed-out browser. Copy the final URL after any redirects.
  2. Choose the homepage, one busy collection and one important product page. Include a product with reviews, variant selectors or other app widgets.
  3. Open Layzr, sign in, enter the storefront URL and choose General audit. Select Mobile, then Run audit. Read the Scores and technical findings. Use a separate Desktop run when needed; each audit uses credits.
  4. Keep Shopify's real-user data separate from Layzr's technical scan. If a scan is unavailable, do not interpret missing metrics as zero or as a successful test.
  5. Repeat a slow page test before editing. Save the individual metric values and diagnostics, not just the overall score.

3. Match the fix to the slow component

  • Large first-screen product or hero image: inspect the image identified in the LCP diagnostic. Check its delivered size, dimensions and loading behavior before compressing every image on the store.
  • Long script tasks or slow variant selection: list app embeds and storefront scripts used on that template. Test disabling one optional feature in a duplicate theme. Keep payment, consent and required commerce features intact.
  • Content jumping below a review widget or promotion: reserve the space the component needs and retest the same interaction.
  • Only a collection page is slow: compare its product count, filters and image loading with a faster collection. A theme-wide replacement may be unnecessary.

4. Verify speed and the purchase flow

After publishing a tested change, repeat the same lab tests and exercise the menu, variant selector, cart and checkout entry on a phone. Watch the real-user report over time: it will not update as quickly as a fresh Lighthouse run. A faster test is useful only if customers can still complete the shopping task.

Speed is one part of a page review. Use the landing page audit checklist to check the offer, product explanation, proof and next action. Read the PageSpeed Insights guide if the field and lab results disagree.

Documentation

Review the rest of your product page

Layzr reviews page copy, design, UX and SEO and can use available performance scan context to help explain fixes. Verify technical changes with repeat measurements.

Explore the AI website audit