Shopify app speed audit: find what is slowing your store

Apps can slow loading, delay clicks, or make the page jump. So can themes, large images, tracking tags, and custom code. Your goal is to find a cause you can control without breaking something that helps the store.

1. Start with the symptom, not the app count

Open Shopify’s performance summary from Online Store → Themes, or search the Reports list for Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift. Record the weak metric, device type, affected page group, and date range.

Shopify’s current report uses real-user data, can connect trend changes with app installs, theme updates, and new code, and may lag by up to 36 hours. That makes it better for direction and change history than for an immediate after-click result.

Official source: Shopify web performance reports ↗

2. Fix the test pages and conditions

Choose one representative home page, product page, and collection page. Save the exact URLs. Use the same browser profile, viewport, throttling, cache setting, and test location for every comparison. Run each page several times and compare the median—not the best or worst result.

This page set follows Shopify’s own storefront-app testing model, which measures home, product, and collection pages before and after an app change. Shopify weights product and collection pages more heavily in its app-performance calculation, so do not let a fast homepage hide a weak shopping path.

Official source: Shopify storefront performance testing ↗

3. Record the requests before you diagnose them

1. Open the storefront page in Chrome.
2. Open DevTools and select Network.
3. Enable Disable cache while DevTools is open.
4. Reload the page and interact with the feature you are testing.
5. Filter for JS, then review Domain, Size, Time, and Initiator.
6. Save a sanitized HAR only if you need to share or compare the trace; review it before sending.

Chrome can show what started a request, what it depends on, how long it took, how large it is, and which JavaScript called it. That is much more useful than guessing from a file name.

Official source: Chrome DevTools Network reference ↗

(() => {
  const currentHost = location.hostname;
  const rows = performance.getEntriesByType("resource")
    .map((entry) => {
      const url = new URL(entry.name);
      return {
        host: url.hostname,
        type: entry.initiatorType || "other",
        transferKB: Math.round((entry.transferSize || 0) / 1024),
        durationMS: Math.round(entry.duration),
        path: url.pathname.slice(0, 90)
      };
    })
    .filter((row) => row.host !== currentHost)
    .sort((a, b) => b.transferKB - a.transferKB);

  console.table(rows);
  return rows;
})();

4. Work out where each request comes from

Make a short table with the host, file path, initiator, page, likely source, and how confident you are. Compare it with current and old apps, theme embeds, theme code, pixels, tag managers, and cookie tools.

A third-party web address does not always identify an app, and a large download is not automatically the worst problem. If you are unsure where a request comes from, mark it as unsure.

5. Make one change you can reverse

Use a duplicate theme or a quiet testing window. Disable one app embed, integration, or optional feature—not everything at once. Test the same pages in the same conditions. If the app can load only on selected pages, try that before removing it.

For weak INP, Shopify specifically points merchants toward excessive JavaScript from theme code, app code, or third-party/tag-manager code. The correct action is to clean up the verified offender, not assume every installed app participates in the storefront.

Official source: Shopify performance troubleshooting ↗

6. Decide whether the app is still worth it

Speed is one part of the cost. Also include the subscription, setup, upkeep, overlap with other apps, difficulty of leaving, and the sales or staff time the app can prove it creates. A slightly slower app may still be worth keeping. An unused or duplicated app usually is not.

7. Remove without creating a second problem

Before uninstalling, export needed data, list dependent workflows, note app-managed inventory, confirm whether billing occurs outside Shopify, and read the developer’s removal instructions. Shopify warns that some app code can remain in a theme and that app data or settings may not return after reinstalling.

Official source: Shopify app uninstall guidance ↗

Questions merchants ask

Disclosure and limits

This guide contains no affiliate links. It is an editorial diagnostic method, not a substitute for a qualified developer working on production theme code. MerchantTrim does not receive your console output, HAR files, store URL, or test results.