How to Speed Up Your Shopify Store Without Changing Themes

1. Measure first, and measure the right thing

Test your homepage, a top collection and a top product page in PageSpeed Insights, and look at both the lab results and the field data (real-user Core Web Vitals) where it is available. Note the mobile numbers, since that is where most stores struggle.

Write the results down. Every change below should be tested against that baseline, and our guide to Core Web Vitals explains what the metrics mean.

2. Fix images

• Upload images at a sensible resolution rather than raw camera size.
• Use Shopify's image URL filter with explicit widths and a srcset so each device downloads the right size.
• Set width and height attributes so the layout does not shift as images load.
• Lazy-load images below the fold, but do not lazy-load the main image at the top of the page.
• Give the largest above-the-fold image high fetch priority, since that image is usually the Largest Contentful Paint element.

More detail in our image optimisation work.

3. Audit your apps

Every app can add scripts and styles to your storefront, and removing an app does not always remove its code from the theme.

1. List every installed app and decide which ones still earn their place.
2. Uninstall the ones you no longer use.
3. Search the theme code for leftover snippets and scripts from removed apps, and delete them carefully in a duplicate theme first.
4. For apps you keep, check whether they load on every page or only where they are needed.

See app speed optimisation for how we handle this on client stores.

4. Control third-party scripts

Tracking pixels, chat widgets, review widgets and tag managers are common causes of slow interaction. Load only what you use, defer non-essential scripts, and review your tag manager for tags nobody owns.

5. Trim fonts, CSS and JavaScript

• Use as few font families and weights as your design allows, and set a font-display strategy so text shows while fonts load.
• Remove unused CSS and JavaScript from the theme where you can do so safely.
• Replace heavy sliders, carousels and animation libraries with lighter alternatives or remove them.
• Avoid autoplaying video above the fold.

6. Retest and keep it fast

Re-run your baseline pages after each change so you know what worked. Field data updates over a rolling window, so give it a few weeks before judging the result. Then guard the gains: check speed whenever you add an app or a new section, and consider ongoing performance monitoring.

If the theme itself is the bottleneck after this, that is when a rebuild becomes worth it. See theme speed optimisation.

Frequently asked questions

Can I make my Shopify store faster without changing my theme?

Yes. Images, apps and third-party scripts are usually the biggest causes of slowness, and all three can be improved on your existing theme.

Which Shopify speed fix has the biggest impact?

It varies by store, but properly sized and prioritised images and removing unused apps and their leftover code are the most common big wins.

How do I test my Shopify store speed?

Use PageSpeed Insights on your homepage, a top collection and a top product page, and compare the mobile results before and after each change. Check field data as well as lab data where it is available.