"Why is my store so slow?" is one of the most common questions I hear from owners — and the honest answer is that it's almost never one single thing. It's usually a handful of small weights piled on top of each other. The good news: you don't need to read code to find most of them. Here's the checklist I run through, in plain English.
1. Measure first — don't guess
Before you change anything, get a baseline. Open PageSpeed Insights, paste in your store URL, and read the mobile tab — that's how most of your shoppers actually arrive. Note the score, but pay more attention to the three metrics underneath it: how long the biggest thing on screen takes to appear (LCP), how quickly the page responds when tapped (INP), and whether the layout jumps around as it loads (CLS). Write those numbers down. Now you can tell whether a change actually helped instead of just feeling faster.
2. Check for oversized images
Images are the number-one cause of slow Shopify pages, full stop. A single product photo exported straight from a phone or a designer can be several megabytes — far more than it needs to be on screen. If a hero banner or product image is 3000 pixels wide but only ever displays at 800, the browser still has to download the whole thing. Look for huge background images, full-width banners, and galleries with lots of photos. Shopify resizes images reasonably well, but it can't fix a file that was enormous to begin with. Compress before you upload.
3. Count your apps — and remove the dead weight
Every app you install can add its own scripts and styles to your storefront, and many keep loading on every page even after you've stopped using them. Go to your Apps list and be ruthless: when did you last use each one? That popup app from a campaign two years ago, the review widget you swapped out, the abandoned upsell tool — if it's not earning its place, uninstall it. Removing unused apps is one of the safest, highest-value speed wins there is, and it costs nothing.
4. Question heavy theme features
Themes love to show off. Big auto-rotating image sliders, autoplay background videos, fancy animations, and "mega" menus all look impressive in a demo and quietly tax every visit. A homepage slider often loads several large images the shopper may never even see. Autoplay video is worse — it can pull down megabytes before anyone has decided to stay. Ask yourself whether each flashy feature is actually helping you sell. Often a single strong image converts better than a carousel of five.
5. Test on a real phone, on real data
Your store probably feels fast to you — you're on office Wi-Fi, on a device that's already cached the whole site. That's not your customer. Pick up an ordinary phone, turn off Wi-Fi so you're on mobile data, and load your store fresh. Time how long until you can actually read and tap something. That gap, on a normal connection, is the experience most of your shoppers get — and it's the one worth optimising for.
Where to start
If you only do one thing this week, run PageSpeed Insights and fix your images. Those two steps clear most of the easy wins for most stores. After that, prune unused apps, then take a hard look at any heavy homepage features. Work in that order, re-measure after each change, and you'll see real, honest progress without touching a line of code. The deeper fixes — theme code, scripts, and the order things load in — are where a developer earns their keep, but you can get surprisingly far on your own first.
Frequently asked questions
What is a good Shopify PageSpeed score?
Aim for a mobile score above 50 and ideally 70+, but the field data matters more than the number. Focus on getting Largest Contentful Paint (LCP) under 2.5 seconds and Cumulative Layout Shift (CLS) under 0.1. A green score with a fast LCP on real mobile devices beats a high lab number every time.
Do Shopify apps really slow down my store?
Yes. Many apps inject their own JavaScript and CSS into every page, even pages where the app does nothing. Each one adds requests the browser must download and run. Removing apps you no longer use is one of the fastest, lowest-risk speed wins available to a store owner.
Will a faster store actually increase sales?
Speed is one factor among many, so no honest person can promise a fixed lift. But slow pages measurably increase the share of visitors who leave before the page even loads, especially on mobile data. Removing that friction gives the rest of your store a fair chance to convert.