Here's something that surprises a lot of store owners: Shopify's servers are fast. Really fast. So when a Shopify store feels sluggish, the problem is almost never Shopify itself. It's what's been added on top: apps, images, scripts and years of theme edits.
That's actually good news, because it means most slow stores can be fixed without starting over. These are the twelve causes we find again and again in our speed audits.
First, measure it
Open Google PageSpeed Insights and test three pages on mobile: your homepage, a collection page and a product page. Write down the Core Web Vitals (LCP, INP and CLS) and look at the list of suggestions underneath. If those three letters mean nothing to you, our Core Web Vitals guide explains them in plain English.
The usual suspects
1. Too many apps
Each app can load its own JavaScript and CSS on every page, even pages where you don't use it. Go through your app list honestly. If you haven't touched it in a month, it probably doesn't need to be there.
2. Code left behind by old apps
Uninstalling an app doesn't always clean up after it. We regularly find snippets from apps that were removed a year ago, still loading on every page. A developer can find and remove them safely.
3. Huge images
A 5 MB banner exported straight from Canva or a camera is one of the biggest speed killers we see. Resize images to roughly the size they're shown at and compress them before uploading. Our image guide goes into detail.
4. Homepage sliders
A slider loads several large images at once, and most visitors never swipe past the first. One strong hero image nearly always loads faster and, in our experience, converts just as well or better.
5. Autoplaying videos
Background videos look lovely and weigh a ton. If you use one, keep it short, compressed and muted, with a light placeholder image while it loads.
6. Too many fonts
Every font family and weight is another file to download. One or two families, and only the weights you actually use, is plenty.
7. Tracking scripts
Analytics, ad pixels, heatmaps and chat tools all add weight. Keep the ones you genuinely look at and remove the rest.
8. Chat widgets and popups
Spin-the-wheel popups and chat bubbles often load big scripts right at the start. Set them to appear after a delay or after the visitor scrolls.
9. Images that aren't lazy-loaded
Images further down the page should load only when someone scrolls to them. Modern themes do this, but older or heavily edited themes sometimes don't.
10. The main image IS lazy-loaded
The opposite mistake. The first big image on the page, usually the hero or main product photo, should load straight away. Lazy-loading it makes the page feel slower.
11. An old or over-edited theme
Themes from a few years ago weren't built for today's standards, and years of tweaks pile up. Sometimes the quickest route to a fast store really is a modern theme.
12. Things jumping around
Announcement bars, banners or images without set dimensions push content around as the page loads. It's annoying for shoppers and it hurts your CLS score.
A 20-minute self-check
- List your apps and tick the ones used in the last 30 days.
- Check the file sizes of your homepage banners.
- Count how many fonts your theme loads.
- List every tracking script and pixel.
- Re-run PageSpeed Insights after each change so you know what helped.
When it's time to call someone
If you've cleared out the obvious problems and your mobile score still won't budge, the issue is usually buried in theme code, script order or app code. That's developer territory. Our One-Time Speed Optimization includes a full audit, image and code clean-up, Core Web Vitals work and a before-and-after report, with a minimum Grade B guaranteed within 15 days. If your store changes a lot, Yearly Speed Optimization keeps it fast all year.
Quick answers
What's a good PageSpeed score for Shopify? Don't obsess over the number. Passing Core Web Vitals matters much more. Plenty of successful stores sit somewhere in the 50s to 70s on mobile.
Will removing an app break my store? It can, if the app controls something visible. Test on a duplicate theme first.
Does speed really affect sales? Yes. The slower a page, the more people leave before it even loads, especially on mobile data.
Want us to take a look? See our speed packages or send us your store link.