Shopify Performance Optimization: Reducing TTFB & CLS Issues

Project Overview

Challenge

TTFB: A slow TTFB indicates that it takes too long for the server to respond to a customer’s request, which results in a frustrating experience.

CLS: Cumulative Layout Shift refers to unexpected changes in the layout of a page as it loads. This disrupts the user experience, especially when visitors are trying to interact with elements like buttons or images, only to have them shift unexpectedly.

These issues were negatively impacting the user experience, causing increased bounce rates and lowered conversions. The client’s goal was clear: optimize the performance of their Shopify store to improve load times, enhance stability, and ultimately increase conversions by providing a smooth, seamless experience for their customers.

Industry

Our client operated in the fashion and retail industry, where a fast and frictionless shopping experience is essential. Fashion e-commerce is highly competitive, and customers expect a site to load quickly, especially on mobile devices. Any delay in the shopping experience can lead to lost sales, making performance optimization a critical aspect of their digital strategy.

Platform or Technology Used

The store was built on the Shopify Plus platform, which provides enterprise-level features and scalability. However, even with Shopify’s robust architecture, performance issues like TTFB and CLS can still arise if the site is not optimized correctly. We worked with Shopify’s ecosystem to address these issues while maintaining the store’s high-quality design and functionality.

Technical Assessment

To diagnose the performance issues, we conducted a thorough audit using industry-standard tools like Google Lighthouse, WebPageTest, and Chrome DevTools. Our analysis focused on measuring Time to First Byte (TTFB) and Cumulative Layout Shift (CLS) across key pages, identifying inefficiencies in Liquid code, third-party app requests, and media loading strategies. By pinpointing the root causes, server response delays, unoptimized code, and layout instability, we formulated a targeted optimization strategy to enhance both backend efficiency and front-end stability.

How We Approached the Challenge

Our first step in addressing the performance issues was to conduct a comprehensive audit of the store’s performance. We used several industry-standard tools to measure and diagnose the TTFB and CLS issues:

        TTFB Analysis:

•  We ran tests using tools like Google Lighthouse and WebPageTest to measure the time it took for the server to respond to requests.
• We analyzed the client’s hosting infrastructure and reviewed Shopify’s server performance to determine if the issue stemmed from external factors like server latency or internal factors like inefficient code.

       CLS Evaluation:

• Using Lighthouse and Chrome DevTools, we measured CLS scores across different pages, particularly the homepage, product pages, and checkout flow.
• We identified layout shifts caused by large images, fonts, and dynamic content that caused the page to load in an unpredictable manner.

Our Proposed Solution

We devised a tailored approach to solve both TTFB and CLS issues, focusing on optimizing site speed, improving backend efficiency, and ensuring smooth visual loading. Here’s a breakdown of our proposed solution and the associated benefits:

1. Improving TTFB:

   • Optimizing Shopify Liquid Code: We reviewed and optimized the Liquid code to ensure that it was as efficient as possible. Redundant or unnecessary code was removed to speed up page rendering.
   • Reducing External Requests: We minimized the number of external requests (such as third-party apps and widgets) that could contribute to slow server responses.
   • Optimizing Server Configuration: Shopify Plus stores benefit from fast hosting, but we ensured that the configurations were fine-tuned to handle large amounts of traffic while maintaining speed.

2. Tackling CLS:

   • Setting Explicit Dimensions for Images and Videos: One of the most common causes of CLS is when images or videos load without predefined sizes, causing content to shift when the images finally appear. We set explicit width and height for all media elements to stabilize the layout during the page load.
   • Optimizing Fonts: CLS can be caused when fonts load and shift text unexpectedly. We implemented font-display: swap to ensure text is visible immediately while custom fonts are loading, preventing layout shifts.
   • Lazy-Loading Non-Essential Content: For elements below the fold (like images and videos), we implemented lazy loading. This improves initial page load times and prevents unnecessary layout shifts as content loads dynamically.
   • Reducing JavaScript Impact: We identified and optimized JavaScript that caused layout shifts by preventing any unnecessary scripts from executing during the initial page load.

3. Enhancing Mobile Performance:

   • Mobile optimization was a key focus since a large portion of the client’s audience was mobile users. We ensured that mobile-friendly design elements were lightweight and that the site would load quickly on any device.

Set-up of Implementation Time and Team

We set a 4-week timeline for the project, broken down into the following phases:

1. Week 1: Technical assessment, benchmarking of TTFB and CLS, and identification of areas for improvement.
2. Week 2-3: Code optimization, image and font management, and backend performance improvements.
3. Week 4: Testing, quality assurance, and final implementation. We then monitored the store’s performance over the following weeks to ensure sustained improvements.

The implementation team consisted of:

• Project Manager overseeing timelines and communication.
• Shopify Developers specializing in Liquid and performance optimization.
• UX/UI Designers focused on layout, mobile design, and user experience.
• Backend Developers handling integrations and server performance.

Results of the Implementation

Our optimization efforts led to significant performance improvements: TTFB was reduced by 30%, ensuring faster server response times, while CLS scores improved by 50%, eliminating disruptive layout shifts. Overall, page load times improved by 25%, particularly benefiting mobile users. These enhancements translated into a 12% increase in conversions, as a smoother, faster shopping experience kept users engaged and reduced bounce rates.

Showcase Results After Implementation

The results of the optimization were impressive, with measurable improvements across several key performance indicators (KPIs):

• TTFB Improvement: After optimizing the server configuration and Liquid code, we saw a 30% reduction in Time to First Byte. This significantly improved the user experience, as the page started rendering much faster.

• CLS Reduction: We managed to reduce the CLS score by 50%, stabilizing the layout and making the site much more user-friendly. The removal of layout shifts during the loading process kept users engaged and reduced frustration.

• Page Load Time: Overall, we achieved a 25% improvement in page load time, especially on mobile devices. This translated directly into better customer engagement and lower bounce rates.

• Conversion Rate Increase: The improved site performance contributed to a 12% increase in conversions. Faster, smoother shopping experiences directly impacted the client’s bottom line, with users staying longer on the site and completing purchases with less friction.

Next Steps

The initial results were promising, but there’s always room for further optimization. To continue improving the Shopify store’s performance, we recommend the following next steps:

• Ongoing Performance Monitoring: We will continue monitoring performance, particularly around peak traffic times. Regular performance audits will ensure that the site remains optimized as new features and apps are added.
• Advanced Personalization: We plan to integrate personalized product recommendations and dynamic content loading, which can further enhance user engagement and drive conversions.
• SEO Improvements: With improved speed, the next step is to optimize the store for SEO to ensure that the fast performance also translates into higher search engine rankings and organic traffic.

Lessons Learned

Through this project, we learned several valuable lessons:

• Performance Optimization is an Ongoing Effort: While initial improvements were significant, performance optimization is not a one-off task. It requires continuous monitoring, especially as the site evolves and new features are added.

• Balancing Design with Performance: Ensuring that the site looks great while loading quickly requires a careful balance. Using tools like lazy loading and font optimization without compromising design helped us strike the right balance.

• Collaboration Across Teams: Effective communication between developers, designers, and project managers was key to ensuring the project ran smoothly and that performance issues were addressed comprehensively.

Optimizing a Shopify store’s performance is essential for maintaining a competitive edge in today’s e-commerce landscape. By addressing TTFB and CLS issues, we were able to improve load times, enhance user experience, and increase conversions for our client. If you’re facing similar performance issues on your Shopify store, a comprehensive optimization plan can yield impressive results. Ready to improve your store’s performance? Book a free consultation today and see how Frontlevels can help you achieve the best results for your Shopify store.