Core Web Vitals, Observability, and Uptime: How Leading Retailers are Maintaining Performance During Peak Periods

By Manesh Tailor

Today’s online shoppers will wait for no one.

Often-cited data from Google shows that 40% of users will leave a site if it takes more than three seconds to load. A study from Portent found that a B2B site that loads in one second has a conversion rate five times higher than a site that loads in 10 seconds.

For retailers, performance isn’t just about having a fast website. It’s also about strong search engine results: 92% of traffic to a retailer comes from Google searches. In 2020, Google tied search engine results and website performance together even more closely when they established Core Web Vitals (CWV): a set of metrics that measure real-world user experience online.

Maintaining strong website performance and uptime is mission critical for retailers, and CWV have become crucial signals when it comes to maintaining and improving that performance. Using observability for CWV allows retailers to detect anomalies before they impact the user experience, while also identifying opportunities to optimize performance.

Understanding Core Web Vitals

In 2020, Google's Chrome Team introduced CWV to provide a suite of useful quality signals for websites. The following year, Google began using Core Web Vitals as a ranking factor, meaning websites that offered a solid user experience were prioritized in search results over those that did not. CWV include:

• Largest contentful paint (LCP): How quickly does the main content of a page load? Monitoring LCP helps identify areas for improvement and ensures the website loads swiftly across different devices and network conditions.
• Cumulative layout shift (CLS): Does a page’s layout change unexpectedly while it’s loading? Sudden changes can annoy users, especially if they accidentally click on the wrong thing because of a layout shift.
• Interaction to next paint (INP): How long does it take for something to change visually after a user interacts with a page? This is Google’s newest CWV: INP emphasizes the interval to visual feedback, which indicates perceived responsiveness.

By actively monitoring CWV, retailers can identify performance issues, prioritize optimizations, and ultimately provide a better user experience on their website. Improving CWV can be tied directly to business outcomes: higher search engine rankings, stronger user engagement, and increased revenues.

How monitoring impacts Core Web Vitals

For leading retailers, observability plays a key role in staying on top of CWV and ensuring eCommerce sites operate smoothly. Retailers use observability to monitor key performance metrics including page load times and browser rendering. This visibility allows engineering teams to pinpoint areas that need improvement and prioritize optimization efforts effectively. For high-volume retailers, identifying and optimizing pages with the highest traffic levels can lead to outsized improvements in efficiency — and revenue growth.

Observability accelerates the incident response process — a key capability for retailers managing surges in traffic. When observability platforms integrate with tools like Slack or Jira, developers are immediately alerted to incidents and performance issues with the necessary context to understand root causes and implement targeted solutions.

Leading retailers recognize the value of observability for both high-level monitoring and detailed performance insights: from summaries of CWV scores to detailed filtering that allows users to segment data based on various attributes for granular analysis. Retailers with mature observability practices use these tools to zero in on user behavior across device types, browsers, operating systems, and geographic locations of page access — ensuring they maintain strong CWV scores for all audiences.

Maintaining performance in peak traffic

Every retailer must be able to scale their eCommerce infrastructure to accommodate increases in traffic. Maintaining reliable performance is crucial during periods of peak traffic — not only predictable surges like Black Friday and special sales events, but also unexpected surges that can take place when a product or ad campaign goes viral. Successful retailers take a proactive approach to peak traffic, monitoring CWV and setting up their infrastructure to scale rapidly when necessary. Outages can damage a brand’s reputation, and they can also have a direct impact on the company’s bottom line. The 2024 Observability Forecast found that the median annual cost of an outage was US$400 million, and could go as high as US$1.2 billion. These costs can be particularly damaging for retailers where uptime is directly correlated with revenue — when customers can’t access the site, they can’t make purchases.

Kurt Geiger , the global footwear and accessories brand, operates several websites and retail stores across the UK and Ireland. Recognizing the importance of the digital customer experience during peak periods, Kurt Geiger uses proactive observability strategies to maintain performance. Before the European summer and Black Friday sales, Kurt Geiger reviews alert thresholds and examines coverage gaps to ensure developers will be immediately alerted to critical issues.?

Core Web Vitals are a fundamental part of Kurt Geiger’s approach to performance and uptime. The company uses custom instrumentation to ingest CWV data into New Relic. That data is collected and displayed in a dashboard, which provides the company’s engineers with an at-a-glance view of website performance, as well as signals on what improvements need to be made.?

Kurt Geiger built alerts with New Relic Query Language (NRQL) to emerge from this data in case the retailer falls below industry standards. Teams understand what’s happening in real time and have the ability to build and monitor their own alerts, running everything from coding to production.?

Six months after launching the project with New Relic, Kurt Geiger saw its Core Web Vitals score jump from 45-50 to 85-90 — an improvement that has a direct, noticeable impact on customer experience and revenue. The company’s success shows how retailers can lean into Core Web Vitals to improve their digital customer experience — especially in peak periods — and overall business results.?