HeadSpin Proposes Speed Optimizations as Perfect Pick for Carrefour


Overview and Methodology For Our Analysis




iPhone XS / Orange / Paris

Products Used:

HeadSpin Connected Intelligence Platform


  • Review multiple 3rd party SDKs that cause slowdown in launch time
  • Resolve HTTP Redirect issues
  • Optimize connection reuse
  • HeadSpin analyzed the latest version of the Carrefour website on a real iPhone XS in Paris, on the Orange network.
  • NO SDK, code change or instrumentation was needed to run the remote performance sessions.
  • HeadSpin’s AI engine sifted through network traffic, client-side metrics, and videos of the test execution to find areas of poor user experience and performance bottlenecks.
  • Recommendations were provided for every issue that was surfaced.

Insights and Recommendations

HeadSpin’s proprietary AI technology analyzes and prioritizes the core issues impacting critical user journeys. Using computer vision techniques to quantify blank screens, time to interact, loading time, loading or buffering animations, and content quality, our AI models can automatically diagnose server-side issues whether they arise from infrastructure deployment issues, poor performance, or API errors. For a custom analysis of your app, request a Performance Insight report from HeadSpin. 

HeadSpin Performance Session (link)


Analysed KPIs

Launch Time     7 sec  
   Search for an item     6.5 sec   
   Signup   4 sec

The sample performance analysis focusing on a typical critical user journey for Carrefour. Following are the top performance areas that can be optimized for Carrefour (Mobile Web App).

Connection Reuse On a number of occasions the app didn’t reuse already opened TCP connections which adds additional overheads.

HTTP Redirects Some HTTP requests were redirected which can incur additional response times.

Slow TLS The application waited longer than 300 ms to complete TLS handshakes some of the hosts which is considered slower than optimal.

The app can benefit from further detailed analysis into the different performance affecting issues which Headspin can assist with. One example is how does the app perform at different times of the day in particular during peak times? How does the app perform on different devices with different specs, or in different cities?

We have analyzed the overall performance during the below key journeys in order to identify any bottlenecks or performance issues.
   Time to first interaction      7 sec  

The time it takes for your users to start interacting with the app is of great importance and should be minimized as much as possible. We have used the below screen as our control screen to measure the the Time to First Interaction (TTI).

   Signup                                   6.5 sec
How long it takes for your users to sign up can be quite crucial to your conversion metrics. The number of steps it takes to successfully sign up your users is equally as important as the time it takes to execute the required steps. During our sessions we have focused on how long it took for your users to signup excluding any additional time due to user input.
   Search and add an item      4 sec

The time it takes to return a search result and to add an item to a basket is quite important to ensure a smooth user experience.

During our sessions we have encountered the below issues that might affect the overall performance of the website when executing the above user journeys. Please note that the below issues are just examples of the issues we have encountered and there might be more instances of those issues. For more information on the below issues please visit the recorded session.

Performance Issues

Connection Reuse

TCP connections come with their own overheads, everytime a connection is opened those overheads add to the time of the task being executed.

The app created multiple connections in close succession to the same hosts.


HEADSPIN RECOMMENDATION: Check the keep-alive settings on the host server. If keep-alive connections aren’t enabled, or if the keep-alive timeout is set too low, client connections will be terminated prematurely, resulting in unnecessary TCP/TLS handshakes.

HTTP Redirects


Some of the HTTP requests made by the website were redirected. We have included the below examples for your reference.
 Impact Time (ms)  Status Code    Status Message URL URL of Redirected Target
21307 Temporary RedirectLink/dms?tc_firsttime=1
22307 Temporary RedirectLink/dms?tc_firsttime=1
24302 FoundLinkn/a
26307 Temporary RedirectLink/dms?tc_firsttime=1
HEADSPIN RECOMMENDATION: HTTP redirects can be costly, especially if they redirect to a new host, which can incur additional DNS, TCP, TLS, and request-response roundtrips and thus add unnecessary delay.

Slow TLS

Your application waited longer than 300ms to complete TLS handshakes with some hosts. We have included the slowest one. More information can be found on the recorded session.
TLS handshakes add latency to requests due to additional round trips between the device and server. Consider moving your servers closer to users or using a CDN to cut down on round trip time.
HEADSPIN RECOMMENDATION: Consider enabling keep-alive to reuse established connections. Examine the costs of additional overhead incurred by any domain sharding optimizations. Consider caching strategies to reduce or eliminate handshake round trips.

How to Work With HeadSpin

HeadSpin Powers Flawless Mobile App Performance

HeadSpin’s state-of-the-art Digital Experience Intelligence Platform™ will empower your engineering teams to:

  • Execute automation tests on real carrier-enabled devices worldwide
  • Discover performance bottlenecks
  • Collect and visualize your performance data
  • Seamlessly integrate with your CI/CD workflow
  • Monitor every critical user flow of your mobile experience
  • Pinpoint issues that cause performance regressions and impact user experience earlier in your development cycle
Overarching Areas of Opportunities

  • Launch new features confidently by monitoring and analyzing root causes of performance issues throughout the development life cycle
  • Drive new user installs and user engagement with optimized performance
  • Forge user trust and safety, accelerating consumer services for critical user paths across your apps and website
  • Benchmark KPIs for mobile performance to understand how your user experience for your mobile app and website compares to your peers in the same industry
  • Support localized testing across 32,000+ devices and 160+ countries around the world, on real devices under real-world conditions
Expert Holistic Consultation and Strategy 

HeadSpin has the product and solutions expertise to help you perfect the digital experience for your customers! Our team hails from digital pioneers, such as Google and Facebook, and has already delivered enhanced mobile-centric experiences for a diverse set of Fortune 1000 clients. HeadSpin’s strategic insights can help you:

  • Drive new user acquisition, user engagement, and feature adoption
  • Deploy app security measures on iOS and Android
  • Build consistent performance standards and experiences across all your mobile apps and websites 

... insight from HeadSpin helps us prioritize issues so we could deliver a better user experience.

Maria Zhang, CTO, Tinder