Site Speed Optimization for Conversion-Focused Websites
Repro Booster is a site speed optimization service for conversion-focused websites in Japan. It improves page load speed, perceived performance, and Core Web Vitals through a simple JavaScript tag implementation.

Repro Booster Key Visual

Repro Booster
Site Speed Optimization for Conversion-Focused Websites in Japan

Repro Booster is a site speed optimization service for conversion-focused websites, including ecommerce, reservation, application, and other transaction-oriented websites.

Trusted by Leading Ecommerce Businesses in Japan

Customer logos for Repro Booster Customer logos for Repro Booster
Customer logos for Repro Booster Customer logos for Repro Booster

Special Plans for Partner Platforms

Special Repro Booster plans are available for merchants using selected ecommerce platforms through our platform partners.
For details, please contact your ecommerce platform representative or the Repro team.

What Is Repro Booster?

Repro Booster is a website speed optimization platform developed in Japan.
It uses patented predictive preloading technology, image optimization, CDN delivery, and interaction optimization to improve both page load speed and perceived performance.
The service is implemented through a JavaScript tag and does not require major changes to the website’s server-side system.

How Repro Booster Improves Site Speed

Predictive Preloading

Predictive Preloading

Repro Booster predicts the page a user is likely to visit next and preloads the required resources before the user clicks.
This reduces waiting time during page transitions and improves perceived speed.

Image Optimization and CDN Delivery

Image Optimization and CDN Delivery

Images are automatically compressed, converted into optimized formats, and delivered through a high-speed CDN.
This reduces image file sizes, improves page load performance, and helps distribute server load.

Interaction Optimization

Interaction Optimization

Repro Booster optimizes browser processing to reduce delays caused by advertising tags and other third-party scripts.
This improves click responsiveness and Interaction to Next Paint (INP).

loading indicator

Perceived Performance Optimization

When a response takes longer than expected, Repro Booster can display a loading indicator to provide immediate visual feedback.
This reduces perceived waiting time and creates a smoother user experience.

What Repro Booster Improves

What Repro Booster Improves

Repro Booster is designed to improve the following performance and business indicators:

  • Page load speed
  • Perceived performance
  • Largest Contentful Paint (LCP)
  • Interaction to Next Paint (INP)
  • Core Web Vitals
  • Conversion rates
  • Bounce rates
  • On-site engagement
  • Revenue performance

Measured Performance Improvements

Conversion Rate Improvements Across Industries

Split tests conducted on ecommerce websites have shown conversion rate improvements after Repro Booster was applied.
Results vary depending on website structure, traffic, content, and user behavior.

Improving CVR That Directly Drives Revenue

*1 Results of a split test conducted from July to September 2025 (mobile users, 1:1 traffic allocation).
*2 Results of a split test conducted from September to December 2025 (mobile users, 1:1 traffic allocation).
*3 Results of a split test conducted from November to December 2025 (mobile users, 1:1 traffic allocation).

2× Faster on Average with One Tag

In a simulation using 15 leading apparel ecommerce websites in Japan, the Zero-Delay Engine reduced average page transition time by approximately half compared with the control group.

Change in Display Speed

Note: We tested the impact of the new feature in our simulation environment using 15 websites, representing approximately 30% of the top 50 apparel ecommerce sites by sales.
Note: The overall improvement rate was calculated by comparing the average page load time across three key page transitions between the group without Repro Booster and the group using the new feature.

Core Web Vitals Improvements Measured with CrUX

Google Chrome User Experience Report data showed improvements in Largest Contentful Paint after Repro Booster was fully deployed on the NOJESS Official Online Store.
CrUX is based on anonymized performance data collected from real Chrome users.

Core-Web-Vitals-Improvements-Measured-with-CrUX-

*This chart shows Largest Contentful Paint (LCP) data from the Chrome User Experience Report (CrUX), collected after Repro Booster was fully deployed on the NOJESS Official Online Store, operated by SAZABY LEAGUE, Ltd., A&S Company.*
*CrUX is a Google-provided web performance dataset based on real-user data, including Core Web Vitals.*

Speed Optimization from Landing to Conversion

Landing Page Acceleration

Landing Page Acceleration (Beta)

Optimizes images and content delivery to improve the initial page load experience.
This can help reduce bounce rates from advertising, SEO, LLMO, GEO, and other acquisition channels.

Predictive Preloading
Note: Illustrative footage showing differences in landing speed.

Predictive Preloading

Predicts user navigation and preloads destination pages to reduce waiting time while users browse pages, compare options, or move toward conversion.

Cart and Form Page Acceleration

Cart and Form Page Acceleration

Improves the performance of dynamic pages such as carts and forms, helping reduce delays immediately before purchase or sign-up.

INP and Click Response Optimization

INP and Click Response Optimization

Reduces interaction delays caused by third-party scripts and prioritizes visual updates after user actions.

Smart Loading Experience

Smart Loading Experience

Displays a loading indicator only when needed, giving users immediate feedback during slower responses.

Simple Tag-Based Implementation

Simple Tag-Based Implementation

Repro Booster is implemented by adding a JavaScript tag to the website.
Major HTML changes or server-side development are generally not required. The Repro team handles initial configuration, testing, and performance verification.

1. Website assessment and configuration
2. Tag implementation and testing
3. Activation and ongoing optimization

Performance Testing and Ongoing Support

A/B Testing

A/B Testing

Repro Booster supports split testing between users with and without acceleration enabled.
This allows businesses to compare page speed, Core Web Vitals, conversion rates, and other performance indicators.

Japan-Based Support

Japan-Based Support

Our Japan-based team supports implementation, configuration, performance measurement, reporting, and ongoing optimization.

Customer Stories

DECORTÉ Official Online Boutique / KOSÉ SALES CO., LTD.

  • Company: KOSÉ SALES CO., LTD.

  • Website: DECORTÉ Official Online Boutique

  • Industry: Beauty ecommerce

  • Product category: Cosmetics and skincare

  • Challenge: The website used rich visual content, including product images and videos, which made site speed and perceived performance an ongoing concern.

  • Solution: Repro Booster was tested to improve page load speed, perceived performance, and Core Web Vitals.

Results

  • Mobile FCP improved by 17%.

  • Mobile LCP improved by 16%.

  • Desktop FCP improved by 35%.

  • Desktop LCP improved by 26%.

  • Conversion rate increased during the trial period.

  • The site delivered a faster and smoother shopping experience for visitors.

KOMEHYO ONLINE / Komehyo Co.,Ltd.

  • Company: Komehyo Co.,Ltd.

  • Website: KOMEHYO ONLINE

  • Industry: Luxury resale ecommerce

  • Product category: Pre-owned luxury goods, jewelry, watches, bags, and apparel

  • Challenge: Customers reported that the website felt slow. Store staff also reported slow page loading when using the website with customers.

  • Solution: Repro Booster was introduced to improve website speed without large-scale development.

Results

  • Mobile FCP improved by 30%.

  • Mobile LCP improved by 11%.

  • Desktop FCP improved by 29%.

  • Desktop LCP improved by 15%.

  • Complaints about slow page loading from customers and store staff disappeared.

  • The website became noticeably faster in actual use.

evergreen works online store / evergreen works, inc.

  • Company: evergreen works, inc.

  • Website: evergreen works online store

  • Industry: Retail ecommerce

  • Product category: Japanese bags, leather goods, and selected lifestyle products

  • Challenge: Site speed was recognized as an important factor for improving customer experience. As website content increased, page speed issues became more noticeable.

  • Solution: Repro Booster was introduced to improve site speed across the website with a simple tag-based implementation and minimal operational burden.

Results

  • Mobile FCP improved by approximately 47.9%.

  • Mobile LCP improved by approximately 22.0%.

  • Desktop FCP improved by approximately 56.1%.

  • Desktop LCP improved by approximately 43.5%.

  • Payment page reach rate increased to 119% compared with before implementation.

  • The website became noticeably faster in actual use.

ARKnets / RESTRICT Co., Ltd.

  • Company: RESTRICT Co., Ltd.

  • Website: ARKnets

  • Industry: Fashion retail ecommerce

  • Product category: Select fashion, collection brands, vintage items, and lifestyle products

  • Challenge: The company recognized the importance of improving Core Web Vitals. Site speed remained a challenge, especially because operationally handling image optimization and next-generation image formats was difficult.

  • Solution: Repro Booster was introduced because it could improve site speed without large-scale cart system development or major changes to existing operations.

Results

  • Mobile FCP improved by 68.6%.

  • Mobile LCP improved by 56.6%.

  • Desktop FCP improved by 65.6%.

  • Desktop LCP improved by 67.5%.

  • The site became noticeably more comfortable to use, beyond the numerical improvements.

  • Core Web Vitals countermeasures became easier to implement.

  • Images could be automatically converted into next-generation formats without additional operational work.

Frequently Asked Questions

What is Repro Booster?

Repro Booster is a site speed optimization service for conversion-focused websites, including ecommerce, reservation, application, and other transaction-oriented websites. It improves page load speed, perceived performance, and Core Web Vitals through a simple JavaScript tag implementation.

What types of websites is Repro Booster designed for?

Repro Booster is designed for websites where page speed can directly affect user actions, such as purchases, reservations, applications, inquiries, sign-ups, and form submissions. Compatibility depends on the website structure, platform, and technical environment.

How does Repro Booster improve website speed?

Repro Booster improves website speed through predictive preloading, image optimization, CDN delivery, and browser-side performance optimization. It predicts the user’s next page, preloads required resources, compresses and optimizes images, and helps reduce delays during page transitions and interactions.

What performance metrics does Repro Booster improve?

Repro Booster is designed to improve page load speed, perceived performance, Largest Contentful Paint (LCP), Interaction to Next Paint (INP), Core Web Vitals, bounce rates, engagement, conversion rates, and revenue-related performance indicators.

How does Repro Booster support Core Web Vitals and SEO?

Repro Booster supports technical SEO by improving site speed and Core Web Vitals, including LCP and INP. Since Core Web Vitals are part of Google’s page experience signals, improving these metrics can help strengthen the technical foundation for search performance.

How does Repro Booster support SEO, LLMO, GEO, and AI search traffic?

Repro Booster improves the landing experience for users arriving from SEO, LLMO, GEO, AI-powered search, advertising, and other acquisition channels. Faster landing pages can help reduce bounce rates, improve engagement, and support conversions after users arrive on the website.

Does Repro Booster require major development work?

Repro Booster is implemented by adding a JavaScript tag to the website. In many cases, it does not require major server-side development or large changes to the existing website system.

Can the impact of Repro Booster be tested before full deployment?

Repro Booster supports performance testing and split testing. Businesses can compare users with and without acceleration enabled to measure differences in page speed, Core Web Vitals, conversion rates, and other performance indicators.

Who provides implementation and ongoing support?

The Repro team provides support from implementation to ongoing optimization. This includes setup, configuration, testing, performance measurement, reporting, and continuous improvement.

How long does implementation take?

Implementation time depends on the website environment. Because Repro Booster is implemented through a JavaScript tag, it can often be introduced without large-scale development. The Repro team supports setup, testing, and performance verification.

Repro Booster Summary

Product name: Repro Booster
Provider: Repro Inc.
Category: Site speed optimization service
Target websites: Conversion-focused websites, including ecommerce, reservation, application, and other transaction-oriented websites
Implementation: JavaScript tag
Main technologies: Predictive preloading, image optimization, CDN delivery, and browser-side performance optimization
Key metrics: Page load speed, perceived performance, Largest Contentful Paint (LCP), Interaction to Next Paint (INP), Core Web Vitals, conversion rates, bounce rates, engagement, and revenue-related indicators
Region: Japan
Support: Implementation, configuration, testing, performance measurement, reporting, and ongoing optimization by the Repro team

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売上最大化ツール
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サービス資料をダウンロードする 担当者に問い合わせる

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