Many store owners depend on one tool, chase a “100” PageSpeed score, and still wonder why conversions drop, ads become expensive, or users complain about slow pages.
The truth is that Shopify store speed testing needs to have a structured approach, multi-tool in nature, and must focus on real user experience, not on vanity metrics.
Below, you’ll learn exactly how to test the speed of a Shopify store correctly, which tools you should use, how to interpret the data, and which mistakes to avoid, so performance testing actually leads to revenue improvement.
Why Proper Shopify Speed Testing Matters
Shopify speed directly affects:
- SEO rankings (via Core Web Vitals)
- Conversion rates
- Bounce rates
- Paid ad performance
- Customer trust
According to Google:
-
A 1-second delay can reduce conversions by up to 20%
-
Pages loading slower than 4 seconds lose over 24% of users
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Mobile users are significantly less tolerant of delays than desktop users
Yet many Shopify stores misdiagnose speed issues because they test incorrectly.
Common Shopify Speed Testing Mistakes (Before We Begin)
Before going into tools, it’s important to understand what not to do:
- Testing only the homepage
- Relying on any speed tool
- Ignoring mobile performance
- Testing without incognito mode
- Not separating lab data from real user data
- Optimizing for scores instead of experience
Proper testing fixes these mistakes.
Step 1: Understand the Two Types of Speed Data
Shopify speed test will consider two different data types:
1. Lab Data (Simulated Testing)
- Controlled environment
- Reproducible results
- Useful for debugging
Examples:
2. Field Data (Real User Monitoring)
- Based on real visitors
- Reflects actual device and network conditions
- More reliable for SEO decisions
Examples:
Best practice is to combine them. Lab data tells you what’s wrong. Field data tells you what users experience.
Step 2: Test With Google PageSpeed Insights (Correctly)
Google’s PageSpeed Insights tool is the most misunderstood speed test tool in Shopify.
How to Test Properly:
- Open PageSpeed Insights
- Enter a specific URL (not just homepage)
- Test:
- Homepage
- Product page
- Collection page
- Focus on Mobile results first
Metrics That Actually Matter:
- LCP (Largest Contentful Paint) – Should be below 2.5s
- INP (Interaction to Next Paint) – Less than 200ms
- CLS (Cumulative Layout Shift) – Below 0.1
Ignore:
- “Opportunities” with low impact
- Scores without context
Pro Tip: A PageSpeed score of 70–90 with good Core Web Vitals is often better than a fragile 100.
Step 3: Use Google Search Console for Real User Data
PageSpeed Insight reports some issues. Google Search Console provides real data about actual issues impacting search rankings.
What to Check:
- Core Web Vitals report
- Mobile vs desktop URLs
- Pages marked as:
- Poor
- Needs Improvement
- Good
Why This Matters:
Search Console uses real Chrome user data, not simulations. If URLs are failing here, SEO is already impacted.
Always prioritize fixing URLs marked as Poor over chasing global scores.
Step 4: Test With GTmetrix for Deep Diagnostics
GTmetrix is excellent for technical debugging.
What GTmetrix Helps With:
- Page weight analysis
- HTTP request count
- JavaScript execution timeline
- Third-party script impact
- Waterfall view
How to Test Correctly:
- Choose a test location close to your target audience
- Test on mobile if available
- Compare before-and-after changes
Red Flags to Watch:
- Page size over 3MB
- 100+ HTTP requests
- Long JavaScript execution bars
- Multiple third-party domains are loading early
GTmetrix is especially useful for identifying app-related speed issues.
Step 5: Use Lighthouse for Theme-Level Insights
Lighthouse (via Chrome DevTools) is ideal for theme and code auditing.
Best Use Cases:
- Testing staging or preview themes
- Checking performance before publishing changes
- Identifying render-blocking resources
Key Lighthouse Signals:
- “Reduce unused JavaScript.”
- “Eliminate render-blocking resources.”
- “Serve images in next-gen formats.”
Run Lighthouse:
- In incognito mode
- With browser extensions disabled
- Multiple times for consistency
Step 6: Test Mobile Performance Separately (Critical)
Over 70% of Shopify traffic comes from mobile, yet most stores test on desktop.
Mobile-Specific Checks:
- Touch responsiveness
- Scroll smoothness
- Add-to-cart delay
- Filter interaction speed
Tools to Use:
- PageSpeed Insights (mobile tab)
- Chrome DevTools mobile simulation
- Real-device testing (recommended)
A store that “looks fast” but reacts slowly is still considered slow.
Also Read:- How to Optimize a Shopify Store for Mobile
Step 7: Maintain Performance After Speed Testing
After you have analyzed the performance of your desktop, mobile, Core Web Vitals, and third-party scripts, the next step is to maintain these performance metrics as your Shopify store continues to grow.
Apps, analytics, marketing pixels, and UI upgrades commonly introduce a script post A/B test, leading to performance Regression over time, especially on mobile devices.
To maintain consistency in speed when conducting audits:
- Track scripts that are added after application installations
- Ensure non-critical assets don’t block rendering
- Control when JavaScript and images load across pages
Common Shopify Performance & Speed Optimization Apps
Some of the common Shopify apps, which merchants deploy to help manage performance as their stores grow in complexity, are listed below:
Sonic Page Speed Booster
It focuses more on the improvement of storefront performance controlled by the way scripts, imagery, and assets load. It helps reduce render-blocking resources, supports maintaining Core Web Vitals as apps and tracking tools increase.
Hyperspeed: Extreme Page Speed
Offers front-end optimizations of JavaScript deferring, image optimization, and asset control. Very commonly used in stores running a lot of marketing tools or with heavy themes.
Booster SEO & Image Optimizer
Designed primarily to help with SEO improvements, but does include some features for image compression and cleanup, which can help with loading speed.
Swift Speed Optimizer
It provides features for caching, script management, and lazy loading. Usually used in stores that require basic performance automation without complex manual optimization.
TinyIMG SEO & Image Optimizer
Primarily deals with image compression and SEO metadata. Very useful for the reduction of total page size, particularly regarding image-laden product and collection pages.
Step 8: Test Different Page Types (Not Just Homepage)
Each Shopify page behaves differently.
Pages You Must Test:
- Homepage
- Product page (with variants)
- Collection page (filters enabled)
- Cart page
- Checkout (where possible)
Common issue:
Homepage passes speed tests, but product pages fail due to scripts, images, and variants.
Step 9: Identify Third-Party Script Impact
Many Shopify speed issues come from external scripts, not the theme itself.
How to Spot Them:
- GTmetrix waterfall
- Chrome DevTools Network tab
- PageSpeed “Reduce JS execution time.”
Examples:
- Tracking pixels
- Chat widgets
- Popups
- Reviews apps
- Heatmaps
Testing helps you decide:
- Which scripts are worth keeping
- Which load globally vs conditionally
- Which should be deferred
Step 10: Test Before & After Every Change
Speed testing should be iterative, not one-time.
Always test:
- Before installing an app
- After installing an app
- After theme updates
- After major design changes
- Before large ad campaigns
Maintain a simple performance log:
- Date
- Tool used
- Key metrics (LCP, INP, CLS)
- Changes made
Step 11: Know What “Good Speed” Looks Like for Shopify
Realistic Shopify benchmarks:
- Mobile PageSpeed score: 70–90
- Desktop PageSpeed score: 85+
- LCP: under 2.5s
- INP: under 200ms
- CLS: under 0.1
- Fully loaded time: under 3s (mobile)
Anything slower deserves investigation.
Why Many Shopify Stores Still Feel Slow (Even After Testing)
Because testing alone does not correct problems.
Speed problems often come from:
- App accumulation over time
- Script bloat
- Feature overload
- Marketing tools added without a performance review
When the size of the stores grows, manual optimization becomes a challenge, and this is why control of performance, and not just testing, becomes important.
Wrapping It Up
Testing a Shopify site speed correctly entails clarity, consistency, and context.
When you test the right pages, with the right tools, on mobile first and using real user data.
You stop guessing and begin improving the things that impact SEO, conversions, and revenue.
Fast Shopify sites do not work by accident. They’re tested properly, monitored continuously, and optimized intelligently.
About Gaurav Radadiya
I am co-founder of Adfinite, where we build eCommerce solutions for growth and efficiency. I build highly efficient automations for inventory management, order processing, logistics, returns management, product listing and marketing.
