LCP
Largest Contentful Paint
14.6s
Poor
Good: < 2.5s
Measures how long it takes for the main content to appear on screen
Reduce JavaScript Execution Time
How to optimize nike.com
Next.js SiteScore: 29/100Analyzed February 2026
Reduce JavaScript Execution Time
High Impact+18 points estimated
Why It Matters
JavaScript execution takes 4.2 seconds and blocks the main thread for 1.8 seconds, severely impacting user interactions and TBT.
How to Fix
Remove unused JavaScript (460 KiB savings available) by code-splitting React components and deferring non-critical scripts. Bundle optimize the Kenshoo tracking script and privacy consent modules. In Next.js, use dynamic imports for heavy components and implement route-based code splitting.
0Poor
What This Score Means
A score of 29 falls in the "Poor" range (50-89). While it is better than poor (0-49), you should aim for 90+ to provide an optimal user experience and maximize SEO benefits.
This site is slower than approximately 35% of similar sites. The main issues affecting performance are image optimization, JavaScript execution time, and layout stability.
Addressing these issues could improve your conversion rate by 15-20% and boost your search engine rankings.
Core Web Vitals Analysis
INP
Interaction to Next Paint
410ms
Needs Improvement
Good: < 200ms
Measures how quickly the page responds to user interactions
CLS
Cumulative Layout Shift
0.01
Good
Good: < 0.1
Measures visual stability - how much content shifts during page load
AI Performance Analysis
Nike's UK website has severe performance issues with a score of only 29/100, indicating a poor user experience. The biggest problem is excessive JavaScript execution taking 4.2 seconds and blocking the main thread for 5.7 seconds, which delays the Largest Contentful Paint to a sluggish 14.6 seconds. This React/Next.js site is loading 460KB of unused JavaScript code and suffers from duplicate code across multiple bundles, creating unnecessary network overhead. The most impactful improvements would be removing unused JavaScript, eliminating duplicate modules, and reducing the main-thread blocking time, which could potentially improve Core Web Vitals by several seconds and dramatically enhance the shopping experience.
Other Optimization Recommendations
Optimize LCP Image Discovery
High Impact+25 points estimatedWhy It Matters:
The hero image cannot be discovered immediately from HTML, causing a 2.65-second resource load delay that directly impacts LCP.
How to Fix:
Add fetchpriority='high' to the hero image and ensure it's discoverable in the initial HTML. Move the image src from data attributes to the actual src attribute. For Next.js, use the Image component with priority={true} and remove lazy loading from above-the-fold images.
Fix Page Redirects Chain
High Impact+12 points estimatedWhy It Matters:
Multiple redirects add 1.53 seconds delay before the page even starts loading, directly impacting both FCP and LCP.
How to Fix:
Update the redirect chain from nike.com → www.nike.com → www.nike.com/gb/ to go directly to the final destination. Configure your CDN or server to eliminate the intermediate redirect. Update all internal links to point directly to https://www.nike.com/gb/.
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Related Performance Analyses
More Next.js Speed Tests
Next.js Performance Resources
Eliminate Duplicate JavaScript Modules
175 KiB of duplicated JavaScript from Nike Design System components is loaded multiple times across bundles.
Fix LCP Image Discovery
The LCP image is not discoverable in the initial HTML, causing a 4-second resource load delay.
Remove Unused JavaScript Code
460 KiB of unused JavaScript is blocking the main thread for 7.3 seconds and delaying LCP by 2.4 seconds.
Fix Page Redirects Chain
Multiple redirects add 1.53 seconds delay before the page even starts loading, directly impacting both FCP and LCP.
Frequently Asked Questions
Keep Your Site Fast After Optimization
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