Before checking anything else, run your store through Google PageSpeed Insights and GTmetrix. These give you a starting score and flag the most obvious issues automatically, so you're not checking everything manually from scratch. Note your Core Web Vitals scores specifically, since these are what Google actually uses as a ranking signal, not just a general speed number.
Shopify Speed Audit
Checklist
Checklist
Before paying for speed optimization, it's worth knowing what's actually slowing your store down. This Shopify speed audit checklist walks through what to check, and why it matters, so you can identify obvious issues yourself, or come to a conversation with our team already knowing where to look.
Before You Start: Run a Baseline Test
Before You Start: Run a Baseline Test
Theme code quality:
does your theme include a lot of unused code left over from previous customizations or an old theme version?
Liquid rendering:
are there sections or snippets doing heavier processing than necessary, particularly ones that loop through large product or collection sets?
Third-party script injection:
has code been added directly into theme files by apps that are no longer installed?
File sizes:
are product and banner images uploaded at their original, unoptimized size rather than compressed for web?
Dimensions:
are images being displayed smaller than their actual uploaded size, forcing the browser to download more data than needed?
Format:
are images using modern, efficient formats where supported, rather than older, larger formats?
Lazy loading:
do images below the visible screen load immediately, or only as the visitor scrolls to them?
Video usage:
are autoplaying videos, particularly on the homepage, adding significant load weight?
Installed apps:
how many apps are currently active, and does each one still serve an active purpose?
Script loading behavior:
do app scripts load on every page, even pages where that app's functionality isn't used?
Tracking and marketing scripts:
how many separate tracking pixels and marketing scripts are running simultaneously?
Chat widgets, pop-ups, and review widgets:
are these loading immediately, or can they be deferred until after the main content loads?
Leftover app code:
does theme code still reference apps that have since been uninstalled?
Render-blocking resources:
are scripts or stylesheets loading in a way that delays the page from displaying anything at all?
Unused JavaScript and CSS:
does your theme load code for features or sections that aren't actually used on most pages?
Duplication:
are the same libraries or scripts being loaded more than once, by the theme and by an app separately, for example?
Heavy libraries:
are large JavaScript libraries being loaded for functionality that could be handled with much lighter code?
Why it matters:
JavaScript and CSS have to be downloaded and processed before a page becomes interactive, so unnecessary weight here directly delays how quickly a visitor can actually use the page.
LCP (Largest Contentful Paint):
how long it takes for the largest visible element (often a hero image or main heading) to load. Slow LCP usually points to large images or render-blocking resources.
INP (Interaction to Next Paint):
how responsive the page is when a visitor actually interacts with it (clicking a button, opening a menu). Poor INP often points to heavy JavaScript execution.
CLS (Cumulative Layout Shift):
how much visible content shifts around as the page finishes loading. Poor CLS is often caused by images or ads without reserved space, or fonts loading in and changing text size.
Homepage:
typically image and script-heavy, worth checking first since it usually gets the most traffic.
Collection pages:
performance can degrade with large product counts, particularly if filtering is done client-side.
Product pages:
image galleries, variant selectors, and review widgets often add meaningful weight here.
Cart:
less commonly checked, but cart drawer scripts and upsell apps can add unexpected weight.
Mobile load time:
often meaningfully slower than desktop, particularly on real-world mobile network conditions rather than a fast office wifi connection.
Layout shifts on mobile:
elements that reflow differently on smaller screens can introduce CLS issues that don't appear on desktop.
Touch interaction responsiveness:
does tapping a button or opening a menu feel instant, or is there a noticeable delay?
Mobile-specific image and script behavior:
some themes load different assets for mobile; check that these are actually optimized too, not just the desktop versions.
Redirect chains:
are any URLs passing through multiple redirects before reaching their final destination?
Excessive external requests:
how many separate domains is the page pulling resources from?
Font loading:
are custom fonts loading in a way that delays text from appearing, or causes a visible font swap?
Unnecessary requests:
are there requests firing for functionality that isn't actually used on that specific page?
Slow performance doesn't just delay a page loading, it affects the whole shopping experience: visitors abandon slower pages more readily, navigation and product discovery feel sluggish, and checkout hesitation increases when pages lag during a purchase decision. We won't attach a specific percentage to how much this affects your conversion rate, since that depends on your specific traffic and audience, but the general relationship between speed and engagement is well established.
Impact:
how many pages or how much traffic does this issue affect?
Severity:
is this a minor delay or a significant, visible slowdown?
Effort:
is this a quick fix (compressing a few images) or a more involved change (rebuilding a theme section)?
Business importance:
does this affect a high-traffic, high-conversion page like your bestselling product, or a rarely visited page?
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Get a Professional Speed Audit
Found several issues, or not sure how to fix what you found? Our team can run a full audit and handle the fixes.
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FAQs
A Shopify speed audit is a structured review of what's slowing a store down, checking theme code, images, apps, and technical factors like Core Web Vitals, to identify specific, actionable issues rather than a single generic speed score.
Start with a baseline test through Google PageSpeed Insights and GTmetrix, then work through checks on theme code, images, installed apps, JavaScript and CSS, and mobile performance specifically.
Theme code quality, image optimization, app script impact, render-blocking JavaScript and CSS, Core Web Vitals, and performance separately across your homepage, collection, product, and cart pages.
Google PageSpeed Insights reports LCP, INP, and CLS for any URL, and Google Search Console shows Core Web Vitals data based on real visitor experience across your whole site over time.
Most commonly, unoptimized images, too many apps running scripts on every page, unminified or render-blocking JavaScript and CSS, and theme code that hasn't been cleaned up after previous customizations.
Yes, often significantly. Each app can add its own script that loads on every page, even pages where that app's functionality isn't used, and the cumulative effect of several apps is usually more impactful than any single one.
By compressing and correctly sizing images, removing or deferring unnecessary app scripts, cleaning up unused theme code, and addressing whichever Core Web Vitals metric is scoring poorly, LCP, INP, or CLS.
Running this checklist first helps you understand roughly where your store's issues are, so a professional speed optimization engagement can focus development time on genuine fixes rather than starting from a completely blank diagnostic.