Remove Unused JavaScript and Defer Loading

How to optimize sciencereader.com

Generic SiteScore: 80/100Analyzed February 2026

Remove Unused JavaScript and Defer Loading

High Impact+12 points estimated

Why It Matters

233 KiB of unused JavaScript is bloating your page, with Google Analytics alone wasting 103 KiB (69% unused).

How to Fix

Configure Google Analytics to load asynchronously after page load using gtag defer or move to Google Tag Manager with proper triggers. Remove or defer the unused Swiper library (97% unused, 40 KiB waste) if carousel functionality isn't critical. Use WordPress plugins like Perfmatters to conditionally load scripts only where needed.

0Needs Improvement

What This Score Means

A score of 80 falls in the "Needs Improvement" 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

LCP

Largest Contentful Paint

3.8s
Needs Improvement

Good: < 2.5s

Measures how long it takes for the main content to appear on screen

INP

Interaction to Next Paint

315ms
Needs Improvement

Good: < 200ms

Measures how quickly the page responds to user interactions

CLS

Cumulative Layout Shift

0.00
Good

Good: < 0.1

Measures visual stability - how much content shifts during page load

AI Performance Analysis

This science website has decent but improvable performance with a score of 80/100. The biggest issue is excessive unused JavaScript, particularly from Google Analytics tracking scripts, which wastes 228 KB of data and slows down the site unnecessarily. The site also suffers from poor caching policies (only 1-day cache lifetime instead of longer periods) and render-blocking resources that delay the initial page display by 300ms. Cleaning up unused JavaScript, extending cache lifetimes, and deferring non-critical scripts could easily push this site into the 90+ performance range while significantly improving loading times for visitors.

Other Optimization Recommendations

Optimize Image Compression and Sizing

High Impact+15 points estimated

Why It Matters:

Images are causing 850ms delay to LCP and wasting 280 KiB with oversized and poorly compressed files.

How to Fix:

Compress images using WebP format with higher compression rates - current images can be reduced by 40-60%. Implement responsive images with proper srcset attributes to serve appropriately sized images (your 430x430 images are displaying at only 219x123). Use WordPress plugins like ShortPixel or Imagify for automatic optimization.

Extend Cache Lifetimes for Static Assets

Medium Impact+8 points estimated

Why It Matters:

Short 1-day cache lifetimes for static assets waste 199 KiB on repeat visits and delay LCP by 300ms.

How to Fix:

Set cache headers for JavaScript and CSS files to 1 year (31536000 seconds) since they have version parameters for cache busting. Configure your WordPress caching plugin or server to set longer cache-control headers for /wp-content/uploads/ and /wp-content/plugins/ directories. Use filename versioning to handle updates.

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Generic Performance Resources

Remove Unused JavaScript Code

Google Tag Manager scripts contain 139KB of unused code, slowing LCP by 600ms and wasting processing time.

Optimize Video File Caching

17MB of video content has zero cache lifetime, forcing full re-downloads on every visit and wasting 69MB of bandwidth.

Defer Render-Blocking JavaScript

JavaScript files are blocking initial page render, delaying FCP by 750ms and preventing users from seeing content.

Remove Unused CSS and JavaScript

136KB of unused JavaScript and 63KB of unused CSS waste bandwidth and slow down page parsing.

Frequently Asked Questions

Keep Your Site Fast After Optimization

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