Revenue Growth Through Site-Speed and UX Improvements for Apparel EC

[Engagement Details]
We combined a technical approach that maximized performance without sacrificing the appeal of product imagery — the core competitive asset of apparel EC — with the introduction of a data-driven decision-making process.

• LCP acceleration and PDP optimization: For a site that tends to be heavy due to the extensive use of high-resolution product imagery, we applied next-generation image formats and controlled load priorities. LCP was accelerated from 2.7 seconds to 1.3 seconds. On PDPs, we improved the UI flow for size confirmation and color-variation selection, reducing friction in the purchase consideration process.
• Rebuilding the measurement foundation (GA4 / BigQuery): Moving beyond simple access analytics, we built an advanced analytics foundation by integrating Google Analytics 4 (GA4) with BigQuery. This made it possible to track in detail which initiatives drove revenue or prevented drop-off — making the causal relationships visible.
• Roadmap development through PdM partnership: Rather than running a pure outsourced development engagement, we drove the project hands-on alongside the client's product manager. Based on the data made visible, we prioritized the next initiatives to pursue and jointly developed a mid-term growth roadmap.

[Challenges]

• Trade-off between site performance and image quality: The desire to use imagery to convey product appeal was driving slower page loads and higher bounce rates.
• Low add-to-cart rate: While users reached product detail pages, many did not progress to adding items to the cart due to UX shortcomings in size selection and information gaps.
• Lagging data utilization: Effectiveness validation of initiatives was insufficient, repeated changes were being made on the basis of experience and intuition, and no reliable growth scenario could be drawn.

[Results]

• Improved engagement metrics: Faster page loads and UX improvements drove a 120〜150% uplift in bounce rate and add-to-cart rate. A clear flow was established for users to evaluate products thoroughly and progress to purchase.
• Contribution to revenue and ad efficiency: Higher add-to-cart rates contributed directly to revenue growth and improvements in CPA/ROAS.
• Higher-quality decision-making: With a data foundation and roadmap established, the organization evolved into one capable of running an evidence-based, fast product-improvement cycle.