Shopify's servers are fast. What makes your store slow on a phone is everything you and your apps added on top. The good news: it is removable, and you do not need a new theme first.
Measure before you touch anything
Shopify admin → Online store → Themes shows a speed score. Better: open the store on your phone on mobile data, and run Lighthouse (Chrome → DevTools → Lighthouse → Mobile) on the homepage, a collection and a product page. Write the numbers down. Fixes that do not move them are not fixes.
1. Uninstall apps you do not use — then remove what they left
Every app adds scripts. Many leave code in theme.liquid after you uninstall. Online store → Themes → Edit code → search theme.liquid for the app's name and remove the leftover lines. This single step is the biggest win on most stores we see.
2. Images: size and format
A 4,000-pixel product photo on a phone is waste. Resize to 2,000px max, let Shopify serve WebP, and make sure your theme lazy-loads images below the fold. Hero images: under 300 KB.
3. Cut homepage sections
Twelve sections, three sliders and an Instagram feed is a slow page nobody scrolls. Keep the hero, the best collection, proof, one offer. Everything else is a click away.
4. Two fonts, maximum
Each font weight is a download. Pick one font for headings and one for body, two weights each. System fonts are fastest.
5. Pixels and chat widgets
Meta, Google, TikTok, Klaviyo, a chat widget, a reviews widget — each loads before your products do. Keep the ones that make money, and load the chat widget after the page is interactive.
6. Hero video → image
An autoplaying video background is often a third of the page weight. A sharp still image with a play button keeps the look and loses the weight.
7. Sliders and carousels
Carousels load every slide. Most visitors see only the first. Replace with one strong image or a grid.
8. Reviews and upsell apps
Many load their whole widget on every page. Set them to load on product pages only, lazily.
9. Then, and only then, the theme
If the numbers are still poor after 1–8, the theme is the problem. Dawn and the Online Store 2.0 themes are lighter than most older paid themes. Migrating is a day's work done properly, with your sections rebuilt.
- Measure the three pages on a real phone and in Lighthouse.
- Remove leftover app code and unused apps (with your approval of the list).
- Resize and convert images, fix lazy loading.
- Trim sections, fonts and pixels.
- Measure again, send you the before/after.
Not sure which step you're on? Book a growth call — fifteen minutes with Lee, no pressure, no obligation. You leave with the step, the first fix and the price.
Frequently asked
Why is my Shopify store slow on mobile but fine on desktop?
Phones have less processing power and slower connections, so scripts and large images that desktop hides become visible. Apps and image sizes are the usual cause.
Does a faster Shopify store sell more?
Stores we have trimmed see fewer people leave before the page loads, which is more people reaching the product. We do not promise a number; we send the before and after.
Should I change my Shopify theme to fix speed?
Last, not first. Most speed is apps and images. Change the theme only when the measurements say the theme itself is the ceiling.
How much does a Shopify speed cleanup cost?
Usually US$60–150 depending on how many apps and pages, with the before/after measurements included.