# Lazy Loading Images on Shopify: Speed Gains and Pitfalls

Source: https://storefrontspeedjournal.com/blog/2026-10-24-lazy-loading-images-shopify-speed.html

Reviewed October 24, 2026


Lazy loading defers off screen images so the first screen renders fast. Done wrong it delays the hero image and hurts the metric it meant to help.

## What lazy loading actually changes

A browser normally starts downloading every image on a page as it parses it, so a long product page can queue dozens of images ahead of the one the shopper is actually looking at. Lazy loading tells the browser to postpone images below the fold until the shopper scrolls near them, freeing bandwidth and processing for the first screen.

The result, done well, is a faster first impression and lighter initial page weight, which shows up in Largest Contentful Paint and in how fast the page feels on a mid range phone. Done carelessly, it simply moves the delay to the worst possible place, which is the main image itself.

## The hero image exception

The first large image, the hero or main product photo, should almost never be lazy loaded. It is usually the Largest Contentful Paint element, the thing the speed score is literally timing. Lazy loading it tells the browser to deprioritize the exact resource the metric is waiting for, and scores get worse while the team celebrates implementing a best practice.

Set the hero to load eagerly and consider preloading it, then lazy load everything below: secondary gallery angles, related products, blog thumbnails, review avatars. The rule is distance from the first screen, not a blanket policy applied to every image tag the theme generates.

## Native loading attributes and theme support

Modern themes and browsers support lazy loading through a simple loading attribute on the image tag, which requires no JavaScript library and no extra requests. If a store is paying a performance cost for an old lazy load script, replacing it with the native attribute is often a free speed gain hiding inside a cleanup task.

Check what your theme already does before adding anything. Many current themes ship with sensible lazy loading configured, and stacking a plugin on top creates double handling and layout quirks. Audit first: view the page source, confirm which images carry the lazy attribute, and confirm the hero does not.

## Watch the layout shift side effect

Lazy loaded images need reserved space, width and height dimensions or an aspect ratio in the code, or the page jumps as each image pops in while scrolling. That jumping is measured as Cumulative Layout Shift, annoys shoppers mid read, and can swap one speed problem for another in the scores.

After enabling lazy loading, scroll your longest pages slowly on a phone and watch for jumps, late appearing sections, and images that only load after an awkward pause. A real device scroll test catches what automated scores average away, and it is the difference between a page that is fast on paper and one that feels fast in a hand.

## Related reading

If this topic is useful, these earlier guides go deeper on connected questions: [How Third Party Apps Slow Down a Shopify Store](https://storefrontspeedjournal.com/blog/2026-10-23-third-party-apps-slow-shopify.md), [Image Compression for Shopify: Quality vs Speed Tradeoffs](https://storefrontspeedjournal.com/blog/2026-10-23-image-compression-shopify-tradeoffs.md), and [Why your homepage feels fast but your product pages crawl](https://storefrontspeedjournal.com/blog/2026-10-22-homepage-fast-product-pages-slow.md).

## Frequently asked questions

### Should the main product image be lazy loaded?

No. The main image is normally the element speed tools time as Largest Contentful Paint, so it should load eagerly, with its dimensions set, and ideally be preloaded. Lazy load the images below the first screen instead.

### Does lazy loading improve my speed score automatically?

Only when it was the real bottleneck and the hero stays eager. If images were already optimized and few, gains may be small. Lazy loading a hero image or causing layout shift can make scores worse, which is why you measure before and after.

### Do I need an app for lazy loading?

Usually not. The native browser loading attribute does the job with no extra code, and most modern themes already include it. An app adds weight to solve a problem the browser now handles natively.

### Why do my images jump around while scrolling?

That is layout shift from missing image dimensions. When the browser does not know an image height in advance, it lays out the page without it, then reflows when the image arrives. Setting width, height, or aspect ratio reserves the space.