SEO agency reports 20% traffic decline after applying lazy loading to all images, despite PageSpeed score jumping from 65 to 92, highlighting LCP optimization challenges.

Lazy loading hero image drops traffic 20% despite PageSpeed boost from 65 to 92, LCP rises to 4.2s

An SEO agency experienced a 20% traffic decline after implementing lazy loading across all website images for a client, despite achieving significant PageSpeed improvements, according to a case study shared by Noel Ceta on November 7, 2025. The incident underscores the technical complexity of performance optimization and its relationship with search engine rankings.

Ceta, who operates Apollo Digital and Local SEO, reported that the client’s PageSpeed score increased from 65 to 92 following the lazy loading implementation. However, the optimization proved counterproductive. Traffic dropped 20%, and the site’s Largest Contentful Paint metric deteriorated from 1.8 seconds to 4.2 seconds.

The technical failure centered on a critical implementation error. The agency applied lazy loading to the hero image, which serves as the page’s primary visual element. This decision delayed the loading of the most important above-the-fold content, directly impacting user experience metrics that influence search rankings.

Largest Contentful Paint measures the time required to render the largest content element visible within a user’s viewport. Google maintains specific LCP thresholds, with 2.5 seconds or less classified as good performance and measurements exceeding 4 seconds indicating poor user experience that may negatively affect search rankings.

The case demonstrates the distinction between performance metrics and actual user experience. While PageSpeed scores improved substantially, the critical rendering pathway suffered, causing the site’s largest content element to load significantly slower than before optimization.

Technical mechanics of lazy loading

Lazy loading represents a web development technique that defers the loading of non-critical resources until they become necessary for user interaction. Under standard loading protocols, browsers load all images immediately upon page access, consuming bandwidth and slowing initial page load times. Lazy loading modifies this behavior by instructing browsers to load only visible images initially, with additional images loading as users scroll through content.

The technique delivers legitimate performance benefits for pages containing multiple images. Initial page load times decrease substantially because browsers process fewer resources before rendering visible content. Network bandwidth consumption decreases proportionally, particularly benefiting users with limited connectivity or data restrictions.

However, the implementation requires technical precision to avoid creating performance problems rather than solving them. The specific images selected for lazy loading determine whether the technique improves or degrades user experience.

The LCP implementation rule

The Largest Contentful Paint image must never receive lazy loading treatment, according to current best practices for web performance optimization. This element typically consists of hero images, header images, featured product images, or banners that dominate the above-the-fold viewport area.

Ceta documented the incorrect implementation approach: applying the loading=“lazy” attribute to hero images delays their rendering until after browser parsing completes. This creates a cascading delay effect through the page rendering process.

The correct implementation strategy involves differentiating between above-fold and below-fold content. Images immediately visible when users first access pages should load eagerly using standard protocols. Only images positioned below the initial viewport should receive lazy loading treatment.

For above-fold content, standard image tags without lazy loading attributes ensure immediate rendering. Below-fold images can safely incorporate the loading=“lazy” attribute, enabling browsers to defer their loading until users scroll toward them.

Hidden content complications

Lazy loading hidden content creates additional SEO complications beyond performance metrics. Content embedded within accordions, tabs, or similar interactive elements presents particular challenges when combined with lazy loading techniques.

JavaScript-based content loading systems that fetch content only upon user interaction may prevent search engines from discovering and indexing that content. When content does not exist in the initial HTML and only loads through JavaScript execution, search engine crawlers may fail to access it during their indexing processes.

The problematic pattern involves using AJAX requests to dynamically load content when users interact with specific page elements. Search engines typically see only the empty container elements rather than the actual content that loads through JavaScript execution.

The solution involves including all content in the initial HTML markup while using CSS to control visibility. This approach ensures search engines can access and index the complete content while maintaining the desired user interface functionality.

Buy ads on PPC Land. PPC Land has standard and native ad formats via major DSPs and ad platforms like Google Ads. Via an auction CPM, you can reach industry professionals.

Learn more

JavaScript library considerations

Multiple JavaScript libraries provide lazy loading functionality, each with different implementation approaches and potential pitfalls. The most aggressive libraries can interfere with critical resource loading, creating performance problems similar to those experienced by Ceta’s client.

Common lazy loading libraries include lazysizes, vanilla-lazyload, and the native browser implementation using the loading attribute. The native browser implementation offers significant advantages over custom JavaScript solutions.

Native lazy loading operates at the browser level, requiring no additional JavaScript library downloads or execution. Browsers implement intelligent loading strategies based on viewport position, scroll velocity, and network conditions. The implementation consists simply of adding the loading=“lazy” attribute to image elements.

However, the critical limitation remains unchanged regardless of implementation method. LCP images must never receive lazy loading treatment, whether through native browser support or JavaScript libraries. Ceta reported that the client achieved better results after switching from the lazysizes library to native browser lazy loading, but the fundamental error of lazy loading the hero image caused the traffic decline.

Performance metrics and ranking implications

The relationship between Core Web Vitals metrics and search rankings involves multiple technical factors. Google’s search systems consider Core Web Vitals as ranking signals, though their influence represents a relatively small component within the broader ranking algorithm.

Improper lazy loading implementation delays LCP by forcing browsers to wait for complete page parsing before loading critical images. This delay cascades through the rendering process, potentially pushing LCP measurements beyond optimal thresholds and into ranges that indicate poor user experience.

The ranking impact typically remains relatively minor in most cases, though exceptions exist where performance metrics exert more substantial influence on search positions. The primary concern involves user experience deterioration rather than direct ranking penalties.

However, as Ceta’s case demonstrates, even relatively minor ranking changes can produce measurable traffic effects when compounded across multiple keywords and pages. The 20% traffic decline suggests the LCP degradation affected the site’s visibility across a significant portion of its keyword portfolio.

Context within broader performance optimization

The case illuminates ongoing tensions between different performance optimization objectives. Website operators face pressure to improve PageSpeed scores while simultaneously maintaining fast real-world loading times for critical content.

Technical SEO practices have evolved as Google’s ranking systems have become increasingly sophisticated. Modern ranking algorithms evaluate multiple quality signals derived from webpage content itself, with on-page factors including content relevance, technical implementation, and user experience metrics playing increasingly important roles.

The relationship between performance optimization and search rankings has become more nuanced as machine learning systems have expanded their influence on search results. Google’s quality evaluation extends beyond simple technical metrics to encompass comprehensive assessments of user experience, content quality, and site authority.

Performance optimization must serve actual user experience rather than focusing exclusively on isolated metrics. PageSpeed scores provide useful diagnostic information but do not directly correspond to search rankings. The metrics that most directly affect user experience, particularly those measuring critical content rendering, carry greater importance for search visibility.

Implementation recommendations

Website operators implementing lazy loading should follow a systematic approach to avoid the problems documented in this case. The first step involves identifying the LCP element for each page template, which typically requires performance testing tools to measure rendering times for different page elements.

Once the LCP element has been identified, that element must receive eager loading treatment regardless of other performance optimization strategies. All other images positioned below the initial viewport can safely use lazy loading, with the specific threshold depending on typical viewport dimensions across the site’s user base.

Testing should occur across multiple devices and viewport sizes because LCP elements may vary between desktop and mobile layouts. The image that dominates the desktop viewport may differ from the primary mobile viewport element.

Performance monitoring following implementation provides essential feedback about whether optimizations achieved their intended effects. Core Web Vitals measurements from actual users, rather than laboratory testing environments, provide the most reliable indicators of real-world performance.

Search Console’s Core Web Vitals report offers field data showing how actual users experience the site across different devices and connection speeds. These measurements reveal whether lazy loading implementation improved or degraded the metrics that most directly influence user experience and search rankings.

Industry implications

The case contributes to broader discussions within the search marketing community about balancing technical optimization with user experience. As Google’s ranking systems have evolved to place greater emphasis on semantic understanding and user experience signals, simple technical optimizations have become less reliable as standalone ranking improvement strategies.

Marketing professionals must consider the holistic impact of technical changes rather than optimizing individual metrics in isolation. A PageSpeed score improvement that degrades critical content rendering produces negative rather than positive effects on both user experience and search visibility.

The findings align with guidance Google search team members have provided regarding lazy loading implementation. Martin Splitt and John Mueller discussed lazy loading techniques during a Search Off the Record episode published on August 21, 2025, where they emphasized the importance of distinguishing between critical and non-critical resources when implementing lazy loading.

The case also reflects broader challenges facing website operators as they navigate increasingly complex performance requirements. Traffic patterns have shifted as AI-powered search features and changing user behaviors affect how people discover and access content, requiring more sophisticated approaches to technical optimization.

Subscribe PPC Land newsletter ✉️ for similar stories like this one

Subscribe

Timeline

• November 7, 2025: Noel Ceta reports client traffic dropped 20% after implementing lazy loading across all images, despite PageSpeed score increasing from 65 to 92, with LCP deteriorating from 1.8 seconds to 4.2 seconds
• August 21, 2025: Google publishes Search Off the Record episode 98 addressing lazy loading and SEO implications
• July 17, 2025: Google June 2025 core update brings unexpected recoveries after 16-day rollout, demonstrating connection between technical optimization and rankings
• June 30, 2025: Google confirms June 2025 core update amid website ranking volatility affecting performance-focused sites
• November 2024: Google removes Page Experience Report from Search Console while maintaining individual Core Web Vitals monitoring
• March 12, 2024: Interaction to Next Paint (INP) replaces First Input Delay as Core Web Vital, highlighting performance metric evolution

Subscribe PPC Land newsletter ✉️ for similar stories like this one

Subscribe

Summary

Who: Noel Ceta, operator of SEO agency Apollo Digital and Local SEO service, reported the case involving an unnamed client website that experienced traffic decline following performance optimization attempts.

What: Implementation of lazy loading across all website images caused a 20% traffic decline despite improving the PageSpeed score from 65 to 92. The Largest Contentful Paint metric deteriorated from 1.8 seconds to 4.2 seconds because lazy loading was incorrectly applied to the hero image, creating delays in critical content rendering.

When: Ceta shared the case study findings on November 7, 2025, through a detailed Twitter thread explaining the technical causes of the traffic decline and providing implementation guidance for avoiding similar problems.

Where: The case affects websites implementing performance optimizations across the broader internet ecosystem, with particular relevance for search marketing professionals managing technical SEO for client websites and internal optimization projects.

Why: The traffic decline occurred because lazy loading the LCP element delayed critical content rendering, degrading the user experience metric that influences search rankings. While PageSpeed scores improved through reduced initial resource loading, the optimization harmed the specific performance metric most directly tied to user experience quality and search visibility.