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Tennis Express · Shopify · Shopify Performance

Tennis Express Shopify Performance Optimization

Improving storefront performance by identifying unnecessary JavaScript, third-party scripts, resource prioritization issues, and Core Web Vitals opportunities.

Project timeframe: Performance audit & staged optimization

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Tennis Express Shopify homepage showing Grand Slam Sale hero banners and brand promotional tiles

Tennis Express project snapshot

Brand
Tennis Express
Client
Tennis Express
Industry
Ecommerce / Sporting Goods
Platform
Shopify
Project type
Shopify Performance Audit & Optimization
Services
Shopify Performance, Core Web Vitals, CRO
Integrations
Signifyd, Noibu, SATCB, Alia, Rebuy, Consentmo, Zinrelo, GTM, GA4, Google Ads
Technologies
Shopify, Liquid, JavaScript, CSS, Core Web Vitals, Lighthouse
Timeframe
Performance audit & staged optimization
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Shoppers were waiting on JavaScript before they could evaluate shoes

Tennis Express had Shopify storefront performance issues across key templates—especially shoe product pages—where shoppers waited on a heavy critical rendering path before they could evaluate products.

Audits pointed to a Lighthouse Performance score around 32 on a shoe PDP, LCP near 10.7 seconds, significant JavaScript execution, multiple third-party scripts consuming CPU, a homepage that prioritized the wrong promotional banner, analytics/tracking that needed cleanup, and apps that contributed meaningful execution time.

What we examined for Tennis Express

  • Shopify theme

    Liquid, CSS, JavaScript, fonts, and resource loading across the Tennis Express storefront.

  • Core Web Vitals

    LCP, CLS, and overall page performance on homepage and product templates.

  • Third-party apps

    Signifyd, Noibu, SATCB, Alia, Rebuy, Consentmo, Zinrelo, and related Shopify apps.

  • Analytics

    GTM, GA4, Google Ads, and other tracking that competed for early browser time.

  • Real-user issues

    Noibu session evidence, Safari/iOS behavior, and Quick View functionality.

What we found for Tennis Express

What was slowing down the Tennis Express product pages?

The shoe PDP Lighthouse audit showed JavaScript and third-party scripts as the primary performance constraint—not images or CSS alone. Excessive JavaScript execution delayed interactivity and pushed Core Web Vitals down on Tennis Express product pages.

How do third-party Shopify apps affect Tennis Express performance?

Multiple apps competed for CPU during page load. Approximate CPU times from the audit observations included:

Third-party script CPU observations (audit)

ScriptApprox. CPU time
Signifyd~3.0s
SATCB~1.2s
Noibu~1.1s
Alia~590ms
Rebuy~574ms

These figures are audit observations from the Tennis Express performance review—not permanent production costs.

Why was Tennis Express's LCP so high?

The product page had an observed ~10.7s LCP. Recommendations focused on prioritizing the actual product image and delaying non-critical JavaScript so the largest visible content could paint sooner.

Why was the Tennis Express homepage prioritizing the wrong banner?

The homepage was attempting to prioritize an old or hidden banner rather than the two promotional images shoppers actually saw. In plain terms: the site told the browser to prioritize an image shoppers were not seeing.

What analytics issues showed up on Tennis Express?

We identified opportunities to audit duplicate or unnecessary analytics and advertising scripts—GTM, GA4, Google Ads, and related tags—and reduce their impact on the initial page experience.

Step 01

We improve Tennis Express's Shopify performance

Zqdo combined theme-level optimization with third-party script diagnosis: deferred non-critical JavaScript, audited CSS and fonts, investigated image loading and CLS, used Noibu for real-user errors, and developed a Signifyd mitigation approach that loads fraud tooling when purchase intent appears instead of on every early page load.

Step 02

Shopify apps be loaded without slowing down the storefront

Keep important ecommerce apps, but load non-critical functionality conditionally or after the shopper demonstrates a need for it. Critical storefront rendering comes first; purchase-intent tools wait until they matter.

Tennis Express Nike Rafa Zoom Vapor Cage 4 shoe product page with gallery, size selector, and add to cart
Shoe PDP audited for LCP, JavaScript execution, and third-party script cost—the template where performance constraints were most visible.

Step 03

How the work fits together

A snapshot of the problems this project was built to solve — not a screenshot of the live site.

Tennis Express work-breakdown diagram

Step 04

What this looked like in practice

Collection templates add filter UI, merchandising imagery, and app weight on top of the same shared storefront stack.

Tennis Express Men's Nike tennis shoes collection page with filters and product grid
Collection templates add filter UI, merchandising imagery, and app weight on top of the same shared storefront stack.

What we changed and recommended for Tennis Express

Implemented work is separated from recommendations so we do not imply every opportunity was deployed to production.

Implemented / optimization work

  • Optimized JavaScript loading
  • Changed vendor.min.js preload behavior and used defer
  • Investigated render-blocking resources
  • Audited theme-level CSS and JavaScript
  • Investigated font loading
  • Investigated image loading and lazy loading
  • Investigated CLS / layout stability
  • Investigated third-party app performance
  • Investigated Safari/iOS issues
  • Used Noibu to investigate real-user errors
  • Developed Signifyd script mitigation / conditional-loading approach

Recommendations / opportunities (not all implemented)

  • Further third-party script reduction
  • Conditional loading of non-critical apps
  • LCP image prioritization
  • Analytics / GTM cleanup
  • Font consolidation
  • Additional CSS optimization
  • PDP UX improvement with a "Who This Shoe Is For" summary

Technical implementation for Tennis Express

View technologies and implementation details
  • Shopify theme JavaScript loading and vendor.min.js defer strategy
  • Render-blocking CSS/JS investigation
  • Font loading and image lazy-loading review
  • Core Web Vitals / Lighthouse audits on shoe PDPs and homepage
  • Third-party app CPU profiling (Signifyd, SATCB, Noibu, Alia, Rebuy, and others)
  • Signifyd conditional-loading / purchase-intent mitigation approach
  • Noibu real-user error investigation including Safari/iOS and Quick View
  • Analytics stack review (GTM, GA4, Google Ads)

What results did we see for Tennis Express?

2535

Lighthouse Performance score

Targeted storefront optimizations improved the staging Lighthouse Performance score from approximately 25 to 35. Additional audits identified further opportunities around third-party JavaScript, LCP, and app loading. This staging result should not be read as a proven exact +10 production score change without matching production measurements.

  • Staging Lighthouse Performance improved from approximately 25 to 35 after targeted storefront optimizations.
  • Documented remaining opportunities in third-party JavaScript, LCP prioritization, and conditional app loading.

What changed

Verified results from the work.

Tennis Express's performance challenges were not caused by a single large image or a slow Shopify theme. The larger opportunity was reducing the amount of JavaScript and third-party functionality competing for the browser's attention during the critical rendering path.
  • Staging Lighthouse Performance improved from approximately 25 to 35 after targeted storefront optimizations.
  • Documented remaining opportunities in third-party JavaScript, LCP prioritization, and conditional app loading.

Optimizing when scripts load

A common question in Shopify performance work is how to improve speed without removing important apps. For Tennis Express, the Signifyd work is a clear example.

Default pattern

Page load → every app loads → browser executes everything immediately.

Conditional approach

Page load → critical storefront renders → non-critical functionality waits → purchase intent triggers relevant functionality.

Load non-critical apps conditionally or after the shopper demonstrates a need for them. That protects Core Web Vitals while keeping ecommerce safeguards and merchandising tools available when they matter.

Services used for Tennis Express

Frequently Asked Questions

How did we improve Tennis Express's Shopify performance?

We optimized JavaScript loading, deferred non-critical vendor scripts, audited theme CSS and fonts, investigated image loading and CLS, used Noibu for real-user issues, and developed a conditional-loading approach for Signifyd so fraud tooling did not need to execute at the start of every page load.

What was slowing down the Tennis Express product pages?

On the shoe PDP audit, JavaScript and third-party scripts were the primary constraint. Lighthouse Performance was around 32, with LCP near 10.7 seconds and multiple apps consuming substantial CPU time.

Why was Tennis Express's LCP so high?

The product page's largest contentful paint was observed around 10.7 seconds. Delaying non-critical JavaScript and prioritizing the actual product image were the main LCP recommendations.

How do third-party Shopify apps affect performance?

Apps inject JavaScript that competes for CPU during the critical rendering path. On Tennis Express, audit observations showed Signifyd, SATCB, Noibu, Alia, and Rebuy among the heavier contributors.

How can Shopify apps be loaded without slowing down the storefront?

Keep the apps that matter, but load non-critical functionality conditionally or after purchase intent appears. Critical storefront rendering should come first.

Related resources

Guides related to the Tennis Express work—covering the same platforms, services, and problems addressed in this case study.

Related case studies

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Project lead

David Frempong, founder and digital consultant at Zqdo

David Frempong

Founder & Web Development / Shopify Consultant at Zqdo

David Frempong is the founder of Zqdo, where he works across Shopify development, web development, website management, SEO, AEO, CRO, and technical website optimization. He works with ecommerce brands, local businesses, marketing teams, and development teams to solve technical and growth-related website problems.