Shopify Speed Optimisation
Senior engineers who find out why a Shopify store is slow and fix the cause: app scripts, theme JavaScript, oversized images, fonts and render-blocking code. We measure with real-user Core Web Vitals as well as lab scores, and ship the fixes into your theme.
An engineer reads this and replies. No mailing list, no drip sequence.
- Senior engineers only
- Duplicate-theme testing
- London based
How we speed up Shopify stores
- Measure real-user performance. We start from field data: the Core Web Vitals your real visitors experience on mobile and desktop, by page type. Lab tools such as Lighthouse then show why a page is slow. A store can score badly in a lab test and still pass Core Web Vitals, or the reverse, so we report both.
- Find the causes. We trace every script, stylesheet, font and image that loads on your key templates and attribute it to the theme, an app or a third-party tag. Leftover code from uninstalled apps, unused theme features and tag managers loading everything everywhere are the usual findings.
- Fix in the theme. We remove dead code, defer scripts that do not need to block rendering, load app features only on the pages that use them, serve correctly sized images through Shopify's image CDN, and stabilise layouts that shift as the page loads. Every change is made on a duplicate theme first.
- Verify and protect. We compare before and after lab results straight away and watch field data as it updates. You get a short performance budget and a checklist for installing new apps, so the store does not slow down again six months later.
What's included
- A Core Web Vitals report by page type, using real-user field data and lab diagnostics
- A script and app inventory showing what each one costs in load time and whether it is still used
- Theme fixes for render-blocking code, image sizing, fonts and layout shift, tested on a duplicate theme
- App clean-up recommendations, including leftover code from apps you have already removed
- Before and after measurements on the same templates and devices
- A performance budget and app-install checklist for your team
Speed project timeline
Set after the audit
The audit shows how much of the slowdown comes from the theme, from apps and from third-party tags, and that decides the length of the fix phase. We confirm the timeline in writing after the audit. Field data takes weeks to fully reflect a change, so we keep measuring after the fixes ship.
FAQ
Why is my Shopify store slow?
Usually because of what has been added to the store over time. App scripts that load on every page, code left behind by uninstalled apps, heavy theme JavaScript, uncompressed or oversized images, several font files and third-party tags all add up. The audit attributes each delay to its source so you can see which ones are worth fixing first.
What are Core Web Vitals and what counts as good?
Core Web Vitals are Google's measures of loading, responsiveness and visual stability. A page passes when, at the 75th percentile of real visits, Largest Contentful Paint is 2.5 seconds or less, Interaction to Next Paint is 200 milliseconds or less, and Cumulative Layout Shift is 0.1 or less.
Do you guarantee a PageSpeed score?
No. A Lighthouse score is a lab test on one simulated device, and it changes with every app a store installs. We target the real-user Core Web Vitals that Google uses, report before and after numbers honestly, and explain anything that still fails and why.
Will removing apps break my store?
Not if it is done in order. We list what each app does and where its code runs, test removals on a duplicate theme, and only remove an app from the live store after the duplicate has been checked. Some slow apps are worth keeping; for those we limit where their scripts load.
Do I need a new theme or a headless build to be fast?
Rarely. Many Shopify stores can pass Core Web Vitals on their current theme once dead code, script loading and images are fixed. A theme rebuild makes sense when the theme itself is the problem, and a headless build only when there are other reasons to go headless.
Does site speed affect SEO and conversion?
Core Web Vitals are part of Google's page experience signals, and slow pages lose visitors before they see a product. Speed is one ranking signal among many, but a slow mobile store loses sales it would otherwise make. We focus on the templates that carry your revenue: home, collection, product and cart.
How long before Core Web Vitals improve after the fixes?
Lab results change the same day. Field data in Google's Chrome UX Report covers the previous 28 days of real visits, so it takes up to four weeks for a fix to show fully in Search Console and PageSpeed Insights. We keep measuring through that window.
What do you do about images and fonts?
We serve images through Shopify's image CDN at the sizes each layout actually needs, load the main product or hero image early and lazy-load the rest, and cut font files down to the weights the design uses. On product and collection pages these fixes often make a visible difference.
Can you speed up a headless Shopify storefront?
Yes. On headless builds the causes differ: client-side rendering, large JavaScript bundles, uncached API calls and slow third-party scripts. We profile the storefront, fix rendering and caching first, and set a performance budget for the build pipeline.
How is Shopify speed optimisation priced?
The audit and the fix phase are scoped separately and quoted in writing. The fix quote depends on how many templates are affected and how much of the slowdown sits in the theme versus apps. Some stores only need the audit and a short list of fixes their own developer can apply.
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An engineer reads this and replies. No mailing list, no drip sequence.