This article explains how experienced Shopify teams audit site speed, what they look for, and how they turn findings into practical fixes rather than a list of technical jargon.
Most merchants know whether their Shopify store feels slow. What they don’t always know is why. And without that clarity, speed improvement becomes a guessing game: compress a few images, remove one app, change a theme setting, hope for the best. Sometimes that works. More often it produces marginal gains while the underlying causes remain.
A proper Shopify speed audit is different. It identifies what is genuinely slowing the store down, where that slowdown occurs in the customer journey, and which fixes will have the biggest impact. It also separates “nice to have” improvements from changes that will make a measurable difference to conversion and SEO.
If you’re looking for information on any other part of Shopify site development, head to our Ultimate Guide to Shopify Web Development.
A speed audit starts with context, not tools
Tools are important, but a good audit begins with a simple question: which pages matter most? eCommerce sites are not judged on one URL. A store might have a decent home page but painfully slow product pages. A store might load quickly on desktop and crawl on mobile. A store might be fine for organic traffic but struggle under campaign landing pages bloated with tracking tags.
So the first step is understanding the customer journey. Which products drive revenue? Which collections are popular? Which pages are used in paid campaigns? What is the balance of mobile vs desktop traffic? When you audit the right pages, you discover problems that actually affect trading, rather than optimising obscure templates no one sees.
We typically prioritise the home page, key collection pages, best-selling product pages, cart and mini-cart behaviour, and any landing pages used for marketing. If the store has separate templates for different product categories, those variations matter too.
We look at “feel” as well as metrics
Performance metrics are useful, but they do not tell the full story. A page might technically load quickly but still feel clunky because interactions lag. Another might have a good performance score but still shift around during load, which annoys customers.
So an audit includes real usability checks. We watch how the site behaves on mobile. We scroll on a mid-range device. We open and close menus. We add to cart and adjust quantities. We test variant selectors. We pay attention to where the experience feels sluggish, because those are often the points where JavaScript is heavy or where scripts block the main thread.
This “human” layer of testing is surprisingly revealing. It catches problems that a pure tool-based audit can miss.
Identifying the true culprits: theme, apps, and third-party scripts
On Shopify, the slowdown most often comes from three areas: theme code, apps, and third-party scripts.
Theme issues include overly complex templates, heavyweight JavaScript bundles, repeated code, inefficient Liquid rendering, and poor handling of images and fonts. Sometimes the theme is simply old and not built with modern performance practices. Sometimes it is a newer theme that has been extended without restraint.
Apps are a second major cause. Many apps inject scripts on every page, even when the feature is only used on one template. Over time, stores often accumulate marketing and UX tools that create a crowded script environment. These scripts compete for load time, and they can affect both how quickly the page displays and how quickly it responds to user input.
Third-party scripts include analytics, heatmapping tools, chat widgets, pop-ups, A/B testing scripts, review tools, personalisation engines, and social embeds. Again, any one tool might be acceptable. The combination is where things go wrong.
A speed audit doesn’t just list these tools. It identifies which ones are expensive, which ones overlap in functionality, and which ones can be limited to certain pages or loaded later.
Understanding where time is being spent
A proper audit breaks down the load experience into a few simple questions:
- How quickly does the main content appear?
- What is blocking the page from rendering?
- How much work is happening on the main thread?
- Which scripts are running early?
- Which assets are oversized?
- Are there layout shifts as content loads?
- Are interactions delayed?
Answering these questions usually reveals the root causes. It might be a single heavy script, a font strategy that blocks rendering, a theme bundle that is simply too large, or a combination of apps injecting duplicate libraries.
This is important because it prevents “random optimisation”. Instead of trimming around the edges, you fix what is actually responsible for the slow experience.
Common audit findings (and what we typically do about them)
In many Shopify audits, the fixes are not exotic. They are about understanding how your site works, and finding more economical ways to put it together with all the features that it needs.
We might find images that are being loaded larger than necessary, particularly on mobile, in which case the theme needs better responsive image implementation. We might find that the theme loads a large script bundle globally when only a small portion is needed on most page types. We might find that several apps are injecting sitewide JavaScript, and that some of those scripts can be limited or removed.
We often find that tracking scripts are duplicating work. It is surprisingly common for stores to install multiple tools that each add their own version of similar libraries, or for tags to be installed in several places across the theme and app embeds. Cleaning up tracking implementation can deliver meaningful improvements without damaging marketing capability.
Another frequent issue is “feature creep” in the theme itself. Over time, themes are extended with new sections and features, and those additions are not always built with performance in mind. A speed audit identifies where those features add weight and whether they can be implemented more lightly.
Turning an audit into an action plan
The value of an audit is not the diagnosis, but the prioritisation. Good audits distinguish between changes that will move the needle and changes that are technically correct but commercially insignificant.
We typically group fixes into quick wins, medium-effort improvements, and deeper architectural changes. Quick wins might include image optimisation, script loading adjustments, and removing duplicated tags. Medium-effort work might involve refactoring parts of the theme, improving how sections load assets, or replacing a heavy app feature with theme-native code. Deeper work might involve theme rebuild decisions, major app stack changes, or rethinking how key templates are structured.
That prioritisation helps merchant teams make decisions. Not every store needs a complete rebuild. Many can achieve substantial improvements through targeted work, as long as the right issues are addressed first.
What you should expect from a professional Shopify speed audit
If you commission a speed audit, you should expect more than a list of metrics. You should expect an explanation of what those metrics mean for your customers, a clear list of what is causing problems, and a prioritised plan that reflects your store’s commercial reality.
You should also expect the audit to be honest about trade-offs. Sometimes a feature is worth keeping even if it costs a small amount of performance. The point is to understand the cost and choose deliberately, rather than accepting slow performance by default.
Conclusion
A Shopify speed audit is the fastest way to move from “our site feels slow” to “we know exactly what’s causing it and what to fix first”. Speed issues are usually solvable, but the solution depends on identifying the real culprits – theme architecture, app load, or third-party scripts – and then prioritising fixes that genuinely improve the user experience.
If you suspect your store is slowing down over time, or if you are about to invest in marketing and want to ensure your site can convert efficiently, an audit is a sensible first step. It gives you clarity, reduces guesswork, and helps you spend improvement budget where it will have the biggest impact.
We can provide one for you, with our expert team considering how you can improve performance without impairing functionality. Get in touch to book your audit today.
