Category: Effective Web Performance

Core Web Vitals and Web Performance Strategy: A Reality Check

Google’s Core Web Vitals initiative has become a larger part of discussions that we have with customers as they begin setting new performance KPIs for 2021-2022. These conversations center on the values generated by Lighthouse, WebPageTest, and Performance Insights testing, as well as the cumulative data collected by CrUX and Akamai mPulse and how to use the collected information to “improve” these numbers.

Google has delayed the implementation of Core Web Vitals into the Page Rank system twice. The initial rollout was scheduled for 2020, but that was delayed as the initial disruption caused by the pandemic saw many sites halt all innovation and improvement efforts until the challenges of a remote work environment could be overcome. The next target date was set for May 2021, but that has been pushed back to June 2021, with a phase-in period that will last until August 2021

Why the emphasis on improving the Core Web Vitals values? The simple reason is that these values will now be used as a factor in the Google Page Rank algorithm. Any input that modifies an organization’s SEO efforts immediately draws a great deal of attention as these rankings can have a measurable effect on revenue and engagement, depending on the customer.

While conversations may start with the simple request from customers for guidance around what they can do to improve their Core Web Vitals metrics, what may be missed in these conversations is a discussion of the wider context of what the Core Web Vitals metrics represent.

The best place is to define what the Core Web Vitals are (done by Google) and how the data is collected. The criteria for gathering Core Web Vitals in mPulse is:

Visitors who engage with the site and generate Page View or SPA Hard pages and are using recent versions of Chromium-based browsers.

However, there is a separate definition, the one that affects the Page Rank algorithm. For Page Rank data, the collection criteria gets a substantial refinement:

Visitors who engage with the site and generate Page View or SPA Hard pages who (it is assumed) originated from search engine results (preferably generated by Google) and are using the Chrome and Chrome Mobile browsers.

There are a number of caveats in both those statements! When described this way, customers may start to ask how relevant these metrics are for driving real-world performance initiatives and whether improving Core Web Vitals metrics will actually drive improvement in business KPIs like conversion, engagement, and revenue.

During conversations with customer, it is also critical to highlight the notable omissions in the collection of Core Web Vitals metrics. Some of these may cause customers to be even more cautious about applying this data.

  • No Data from WebKit Browsers. None of the browsers based on Webkit (Safari, Mobile Safari, Mobile Safari WebView) collect Cumulative Layout Shift or Largest Contentful Paint values. Recent updates have allowed for the collection of First Contentful Paint, but that is not one of the metrics used in Core Web Vitals. The argument can be made that Safari and Mobile Safari already deliver highly optimized web experiences, but not providing insight into a significant (if not dominant) user population will leave organizations wondering what global performance metrics (i.e., metrics collected by all browser families) they can use to represent and track the experience for all visitors.
  • Limitations in CrUX Data Collection. The data that Google collects for CrUX reporting only originates from Chrome and Chrome Mobile browsers. So, even though Chromium-based browsers, such as Edge and Opera, currently collect Core Web Vitals data, it is not used by Google in Page Rank. This narrow focus may further erode the focus on Core Web Vitals in organizations where Chrome and Chrome Mobile are only one part of a complex browser environment.
  • Performance Delta between Mobile Safari and Chrome Mobile. With only very limited exceptions, Mobile Safari substantially outperforms Chrome Mobile in standard performance measurement metrics (Time to Visually Ready, Page Load, etc.). This forces organizations to focus on optimizing Chrome Mobile performance, which is substantially more challenging due to the diversity in the Android device and OS population. As well, without a proven business reason, getting customers to update their mobile performance experience based on Core Web Vitals data could become challenging once this exception is realized.
  • Exclusion of SPA Soft Navigations. Up until recently, none of the Core Web Vitals metrics were captured for SPA Soft Navigations (see below for changes to Cumulative Layout Shift). This is understandable as the focus for Google is the performance of pages originating from Google Search Results, and navigating from the results will not generate a SPA Soft navigation. However, the performance and experience advantages of SPA Soft Navigations for visitors is almost completely lost to Core Web Vitals.
  • Current Lack of Clear Links Between Core Web Vitals and Business KPIs. Google has been emphasizing the Core Web Vitals as the new the new metrics that companies should use to guide performance decisions. However, there has yet to be much (or any) evidence that can be used to show organizations that improving these metrics leads to increased revenue, conversions, or engagement. Without quantifiable results that link these new performance KPIs to improvements in business KPIs, there may be hesitancy to drive efforts to improve these metrics.

Google is, however, listening to feedback on the collection of Core Web Vitals. Already there have been changes to the Cumulative Layout Shift (CLS) collection methodology that allow it to more accurately reflect long-running pages and SPA sites. This does lead to some optimism that the collection of Core Web Vitals data may evolve over time so that it includes a far broader subset of browsers and customer experiences, reflecting the true reality and complexity of customer interactions on the modern web application.

Exposing the Core Web Vitals metrics to a wider performance audience will lead to customer questions about web performance professionals are using this information to shape performance strategies. Overall, the recommendation thus far is to approach this data with caution and emphasize the current focus these metrics have (affecting Page Rank results), the limitations that exist in the data collection (limited browser support, lack of SPA Soft Navigations, mobile data only from Android), and the lack of substantial verification that improving Core Web Vitals has a quantifiable positive effect on business KPIs.

The Performance Implications of Android Dominance

When working with customers in Europe or who serve their data in the US and Europe, I am stunned when they ask why their performance is so much slower in certain European countries compared to the US.

Glimpsing at some publicly available stats (thank you Statcounter!), the reason is clear: Android is the dominant Mobile platform in Europe.

Mobile OS Breakdown – Europe – March 2021 to March 2022

This doesn’t hold true everywhere in Europe – in the UK (yes, it is still in Europe!), Android and iOS have nearly equal Mobile device market share.

Mobile OS Breakdown – UK – March 2021 to March 2022

But in Germany, the divide is vast, with Android clearly dominating the playing field.

Mobile OS Breakdown – Germany – March 2021 to March 2022

But there is yet another divide that is greater than even the Android/iOS split – the Android version difference. Depending on the country, your performance could be dependent entirely upon the versions of Android that the visitors use.

Starting with Germany in Q1 2022, Android usage is dominated by the three latest OS versions: 10, 11, and 12.

Android OS Breakdown – Germany – 2022-01-17 to 2022-03-27

But in countries like Spain and France, Android/9 is still a prevalent OS. This version of Android runs on much older hardware and is more likely to experience degraded performance compared to those running 11 or 12.

Android OS Breakdown – Spain – 2022-01-17 to 2022-03-27
Android OS Breakdown – France – 2022-01-17 to 2022-03-27

For teams trying to design performant web sites, this is a critical piece of information. While Mobile is the dominant platform, sites need to be designed to deliver excellent user experiences for all visitors. And in Europe, this means Android users.

What can you do?

  • Focus on rendering – Get your critical content and functionality on the page as quickly as possible. Items that are secondary (ads, tracking, marketing, etc.) can be delayed
  • Reduce your JS as much as possible – Older Android versions struggle with hardware limitations, so reducing the upfront JS processing will be critical
  • Optimize your images – Sounds simple enough, but using an image management service that provides the right image for the device that is viewing the content will make your site device appropriate

And, most importantly, use an Android device. If you make your development team use Android for a week, they might get the message that they need to do more to reach into this neglected Mobile population.


If you’re a browser geek like I am, check out this post I wrote in 2009 about the browser stats. The world is a very different place now.

Real User Measurement – A tool for the whole business

The latest trend A key tool in web performance measurement is the drive to implement the use of Real User Measurement (RUM) in a web performance measurement strategy. As someone who cut their teeth on synthetic measurements using distributed robots and repeatable scripts, it took me a long time to see the light of RUM, but I am now a complete convert – I understand that the richness and completeness of RUM provides data that I was blocked from seeing with synthetic data.

[UPDATE: I work for Akamai focusing on the mPulse RUM tool.]

The key for organizations is realizing that RUM is complementary to Synthetic Measurements. The two work together when identifying and solving tricky external web performance issues that can be missed by using a single measurement perspective.

The best way to adopt RUM is to use the dimensions already in place to segment and analyze visitors in traditional web analytics tools. The time and effort used in this effort can inform RUM configuration by determining:

  • Unique customer populations – registered users, loyalty program levels, etc
  • Geography
  • Browser and Device
  • Pages and site categories visited
  • Etc.

This information needs to bleed through so that it can be linked directly to the components of the infrastructure and codebase that were used when the customer made their visit. Limiting this data pool to the identification and solving of infrastructure, application, and operations issues isolates the information from a potentially huge population of hungry RUM consumers – the business side of any organization.

The Business users who fed their web analytics data into the setup of RUM need to see the benefit of their efforts. Sharing RUM with the teams that use web analytics and aligning the two strategies, companies can directly tie detailed performance data to existing customer analytics. With this combination, they can begin to truly understand the effects of A/B testing, marketing campaigns, and performance changes on business success and health. But business users need a different language to understand the data that web performance professionals consume so naturally.

I don’t know what the language is, but developing it means taking the data into business teams and seeing how it works for them. What companies will find is that the data used by one group won’t be the same as for the other, but there will be enough shared characteristics to allow the group to share a dialect of performance when speaking to each other.

This new audience presents the challenge of clearly presenting the data in a form that is easily consumed by business teams alongside existing analytics data. Providing yet another tool or interface will not drive adoption. Adoption will be driven be attaching RUM to the multi-billion dollar analytics industry so that the value of these critical metrics is easily understood by and made actionable to the business side of any organization.

So, as the proponents of RUM in web performance, the question we need to ask is not “Should we do this?”, but rather “Why aren’t we doing this already?”.

Effective Web Performance – Will A CDN Really Solve The Problem? – UPDATED!!!!

Content Delivery Networks (CDNs) have been available for over a decade, with companies leaning on these distributed networks to accelerate the delivery of their content, absorb the load of the peak traffic periods, and help deal with the problem of geography. During my career I have helped companies assess and evaluate CDN solutions so that they understood the performance improvement benefit they would receive for the money they were spending.

But a something bothered me during these evaluations. I felt that companies were rushing into the decision because it was the “right” thing to do, that their site could only get faster if they used a CDN. This rush often left question unasked and unanswered.

In this post, I want to provide 4 questions that you should ask before deploying a CDN, questions that will help you ensure that a CDN is the performance improvement solution you need right now.

Is the performance issues due to slow application components?

If the performance issue can be tracked down to application elements, then a CDN is likely not the immediate starting point for you and your team. If generating dynamic content or database lookups are causing the performance issue, this is on you, in your datacenter.

CDNs do not make slow applications run faster; CDNs move bits to customers faster more efficiently.

[UPDATE: There are now CDN solutions that can move processing to the Edge (see Akamai Edgeworkers)]

How are we measuring page response times?

If you are measuring response times using the load time of the entire page, then you may be inflating your response times by including all of the third-party content that has been included. You may want to set up parallel measurements that allow you to compare the full page with a page measurement that only includes the content you are directly responsible for managing. If you find that third-party content is slowing down your pages, then a CDN can’t help you.

Full page load times only give you one performance perspective. Modern performance measurement teams need to understand how long it takes for a page to be ready and usable for the customer – the perceived rendering or page ready time. What you could discover is that customers can do 90% of what they want on your page well before all of the content fully loads. If this is true, than the perceived load time for your company to determine that a CDN isn’t necessary right now.

[UPDATE: Google’s Web Vitals metrics are an example of how far the industry has evolved since I wrote this post a decade ago. As well, ensure that your organization does not have tunnel vision on a single performance metric!]

Have we done everything to optimize our own performance?

Often companies choose the easy way (CDN) to solve a hard problem (improve performance). Unfortunately, the easy way can be more expensive than taking the time to design pages and content that ensure long-term and sustainable performance. A CDN could mask a bad design until it slows down so much that even the CDN can no longer help.

Measure your page and challenge the devops team to tweak the exiting design until they don’t think they can get any more performance out of it. Then, during your CDN evaluations, set up measurements that compare the performance of origin and CDN delivered pages. You might find that making the pages as fast as you possibly can before purchasing the services of a CDN make the difference between the origin and CDN times less dramatic than they would have been before optimization.

[UPDATE: I have been doing web performance for 23 years and organizations are still challenged with the design and implementation of performant web applications before they reach the CDN. If the median TTFB for key pages is greater than 500ms, start there.]

Can we effectively estimate if the CDN cost will be offset by an increase in revenue?

CDNs don’t come cheap, so choosing to deploy a CDN better pay for itself over time. Challenge the CDNs you are evaluating to present you with ROI calculations that show how their service more than pays for itself and case studies (or customers) that prove that the cost of the CDN was offset by a business metric that can be easily tracked.

Summary

Don’t misunderstand the questions I am posing here: I am still a strong advocate for the use of CDNs. However, the days of companies simply purchasing the services of a CDN because it’s the “right thing to do” are long over.

As companies evolve their perspective on web and mobile performance, they need to ensure they have done everything they can to make their own applications faster. Once the hard work of tuning and optimization is complete, the process of choosing a CDN must include deeper, more probing questions about the performance and business benefits that come along with the service.

Performance Trends for ???? – Smarter Systems

IF-repair by Yo Mostro (Flickr)

Most of the trending items that I have discussed in the last two weeks are things that can be done today, problems that we are aware of and know need to be resolved. One item on my trend list, the appearance of smarter performance measurement systems, is something the WPO industry may have to wait a few years to appear.

A smarter performance measurement system is one that can learn what, when, and from where items need to be monitored by analyzing the behavior of your customers/employees and your systems. A hypothetical scenario of a smarter performance measurement system at work would be in the connection between RUM and synthetic monitoring. All of the professionals in WPO claim that these must be used together, but the actual configuration relies on humans to deliver the advantages that come from these systems. If RUM/analytics know where your customers are, what they do, and when they do it, then why can’t these same systems deploy (maybe even create and deploy!) synthetic tests to those regions automatically to capture detailed diagnostic data?

Why do measurement systems rely on us to manually configure the defaults for measurements? Why can’t we take a survey when we start with a system (and then every month or so after that) that helps the system determine the what/when/where/why/how of data and information we are looking to collect and have the system create a set of test deployment defaults and information displays that match our requirements?

The list of questions goes on, but they don’t have to. Measurement systems have, for too long, been built to rely on expert humans to configure and interpret results. Now we have a chance to step back and ask “If we built a performance measurement system for the a non-expert, what would it look like?”

More data isn’t the goal of performance measurement systems – more information is what we want.

Performance Trends 2013 – Employees are Customers too

Peter Levine from Andreesen Horowitz wrote an article on The Renaissance of Enterprise Computing yesterday that finally sprouted the seed of an idea that has been dormant at the back of my brain for a few months. While the ideas of enterprise computing and web/mobile performance seem disconnected, they’re not.

When companies begin to rely on outside services (Levine mentions Box, Google Docs, and others in his article) they have given part of their infrastructure over to an outside organization. And, when you do that, this means that any performance hiccups that affect us as consumers can have a very major effect on us as employees.

Even if your company decides to purchase and deploy an enterprise application within your own infrastructure or datacenters, the performance and experience that your employees experience when using it on their desktops or on their mobile devices can affect productivity and effectiveness in the workplace. An unmanaged (read unmonitored) solution can have shut down groups in the company for minutes or hours.

Think of the call-center. No matter the industry you’re in, what increase customer calls: slow performance or a poor experience with the web/mobile application. Now, if your employees rely on a variant of the same web application to answer questions in the call-center, have you actually improved the customer experience and increased employee productivity?

Some considerations when managing, designing, or buying an enterprise application in the coming  year:

  • What do your peers tell you about their experience implementing the solution or using an outside service – has it made employees more effective and efficient?
  • Are employees already using a “workaround” that makes them more effective and efficient? Why aren’t they using the internal or mandated solution?
  • Is performance and experience a driving factor in the lack of adoption of the mandated solution?
  • Do you have clear and insightful performance information that shows when employees are experiencing issues performing critical tasks? Can you clearly understand what the root cause is?
  • Are employees experiencing issues using the application in certain browsers or on certain mobile devices? How quickly can your design or your outside service respond to these issues?
  • Are you reviewing the chosen solution regularly to understand how usage is changing and how this could affect the performance of the application in the future?

Performance issues are not simply affecting the customers you serve. Your own employees use many of the same systems and applications in their day-to-day tasks, so a primary goal of managing these application should be to ensure that the applications deliver performance and experience that encourages employees to use them, no matter whether they are developed in-house or purchased as software or SaaS.

Web Performance Trends for 2013 – Performance Optimization

As we approach the end of 2012, I will be looking at a few trends that will become important in 2013. In a previous post, I identified optimization as an important performance trend to watch. It is one of the items on a performance checklist that companies can directly influence through the design and implementation of their web and mobile sites.

The key to optimization in any organization is to think of objects transmitted to customers, regardless of where they originate, as having a cost to you and to the customer. So, a site that makes $100,000 in a day and transfers 10 million objects to customers has an object-to-revenue ratio of 100. But, if the site is optimized and only 7.5 million objects are transferred to make $100,000, that ratio goes down to 75; and if the reduction in objects causes revenue go up to $150,000, the ratio drops to 50.

This approach is simplistic and does not include the actual cost to deliver each object, which includes costs for bandwidth, CDN services, customer service providers, etc. as well as revenue generated by third-party ads and services you present to customers. The act of balancing the cost of the site (to develop and manage), the performance you measure, the revenue you generate, the experience your customers have, and the reputation of your brand is an ongoing process that must be closely considered every time someone asks, “And if we add this to the site/app…”.

There is no optimal figure for site optimization. But there are some simple rules:

  • Use Sprites where you can. Combing multiple small images into aggregated image maps that you can use CSS to display gives you a double-plus good improvement – fewer objects to download and more text (HTML, JavaScript, and CSS) that can be delivered to visitors in a compressed format
  • Combine JavaScript and CSS files. Listen to your designers – they will likely try to convince that each file needs to be separate for some arcane reason. Listen and then ask if this is the most efficient way to deploy this particular function or formatting. Ask the developer to produce a cost/benefit analysis of doing it their way versus using something that is already in place
  • Control your third-party services. This means having a sane method for managing these services, and shutting them off if necessary. Have every team that is responsible for the site meet to approve (or deny) the addition of new third-party services. And those who want it better come with a strong cost/benefit analysis.

Optimization is the act of making the sites you create as effective and efficient as the business you run. No matter how “low” the cost to operate a web site is, each object on a site can cost the company more money than it is worth in revenue. And if that object slows the site down, it could turn a profitable transaction into a lost customer.

Web Performance – At What Cost? Trends for 2013

image courtesy of Corey Seeman – http://www.flickr.com/photos/cseeman/

As we moved through the traditional start of the holiday shopping season (Thanksgiving / Black Friday / Cyber Monday), it is clear that most sites were prepared for what was coming. No big names went down, no performance slowdowns rose to the headlines, and online revenue – both web and mobile – appears to have increased over 2011.

But when you these companies do their year-end review, they need to take a step back and ask: “Could we have done it better?”

While performance events were few and far between (if they occurred at all), companies will need to examine the cost of scaling their sites for performance. When planning for the peak performance period, companies will need to asses whether simply scaling-up to handle increased traffic and sales could have been managed more effectively, by implementing sites that were not only fast, but  also efficient.

Joshua Bixby (here) noted that web page size has increased 20% in the last 6 months, an indication that efficiency is not always at the top of mind when new web content is presented to visitors. In order to deliver ever more complex web content, companies are spending more on services such as CDNs and cloud services to deliver their own content, while incorporating ever increasing numbers of third-party items into their pages to supply additional content and services (analytics, performance, customer service, Help Desk, and many more) that they have outsourced.

Increasing page size, outside acceleration and cloud services, and third-party services – a potent mix that companies need to asses critically, with an eye to understanding what all of these mean for the performance experienced by their visitors and customers. Add in the increasing importance of the mobile internet, with its variable connection speeds and service quality, and things become even more interesting.

In 2013, I see companies assessing these three trends with a focus on making sites perform the same (or better!) at the same (or lower!) cost than they did in 2012.
Over the next 12 months, I will be watching the performance industry news to see if those companies that have been successful at making their sites perform under the heaviest loads increasingly focus not just on speed and availability, but on efficient delivery of their entire site at a lower cost with the best user experience possible.

The key strategics questions that online businesses will be asking in 2013 will be:

  • Have we optimized our content? This does not mean make it faster, this means make it better and more efficient. It is almost absurdly easy to make a big, inefficient site fast, but it is harder to step back and “edit” the site in a way that you deliver the same content with less work – think Chevy Volt, not Cadillac Escalade.
  • Are we in control of our third-party services? Managing what services get placed on your site is only the first step. Understanding where the content you have added comes from and whether it is optimized for the heaviest shared loads will also become important checklist items for companies.
  • Can we deliver the design and functionality our customers want at a lower cost? This is the hardest one to be successful at, as each company is different. But Devops teams should be prepared to be accountable for not just cool, but also for the cost of creating, deploying, and managing a site.

Managing Performance Measurement: Who uses this stuff anyway?

One of the least glamorous parts of managing performance measurement data is the time I have to take every month to wade through my measurements and decide which stay on and which get shut off. Since I’m the only person who uses my measurement account, this process usually takes less than 10 minutes, but can take longer if I’ve ignored it for too long.

With large organizations that are collecting data on multiple platforms, this process may be more involved. By the time you look at the account, the tests have likely accumulated for months and years, collecting data that no one looks at or cares about. They remain active only because no one owns the test and can ask to disable it.

What can you do to prevent this? Adding some measurement management tasks to your calendar will help prevent Performance Cruft from clogging your information pipes.

  1. Define who can create measurements. When you examine account permissions on your measurement systems, do you find that far more people than are necessary (YMMV on this number) have measurement creation privileges? If so, why? If someone should not have the ability to create new measurements, then take the permissions away. Defining a measurement change policy that spells out how measurements get added will help you reduce the amount of cruft in your measurement system.
  2. Create no measurement without an owner. This one is relatively easy – no new measurement gets added to or maintained on any measurement system without having one or more names attached to it. Making people take responsibility for the data being collected helps you with future validations and, if your system is set up this way, with assigning measurement cost to specific team budgets. It’s likely that management will make this doubly enforceable by assigning the cost of any measurement that has no owner to the performance team.
  3. Set measurement expiry dates. If a measurement will be absolutely critical during  only a specific time range, then only run the measurement for that time. There is no sense collecting data for any longer than is necessary as you have likely either stored or saved the data you need from that time for future analysis or comparisons.
  4. Validate measurement usage monthly or quarterly. Once names have been associated to measurements, the next step is to meet with all of the stakeholders monthly or quarterly to ensure that the measurements are still meaningful to their owners. Without a program of continuous follow-through, it will take little time for the system to get clogged again.
  5. Cull aggressively. If a measurement has no owner or is no longer meaningful to its owners, disable it immediately. Keep the data, but stop the collection. If it has no value to the organization, no one will miss it. If stopping the data leads to much screaming and yelling, assign the measurement to those people and reactivate.

Managing data collection is not the sexiest part of the web performance world, but admitting you have a data collection cruft problem is the first step along the path of effective measurement management.

The Rule of Thirds: The Web Performance Analyst

Blurry Man - Brian Auer - http://www.flickr.com/photos/brianauer/2929494868/

Recently, there has been a big push for the Dev/Ops culture, an integrated blending of development and operations who work closely together to ensure that poor performing web and mobile applications don’t make it out the door. They have become the rockstars of the conference circuit and the employment boards.

I fit into neither of these categories. I have never run anything more than a couple of linux servers with Apache and MySQL. I write code because I’m curious, not because I’m good at it – in fact, I write the worst code in the world and I am willing to prove it!

I am a member of a web and mobile performance culture that is language and platform independent, to use some buzzwords.

I am a web and mobile performance consultant and analyst.

I can take apart reams of data to find statistical patterns and anomalies. I believe that averages are evil, and have believed this for more than a decade. I have been using frequency and percentile distributions for almost as long and watched as the industry finally caught up.

I can link the business issue that faces your company with the technical concerns you are facing and help guide you to the middle ground where performance and the balance sheet are in careful equilibrium.

I don’t care what you write your code in. I don’t care what you run it on. Now, don’t get me wrong: I respect and admire the Dev/Ops folks I have met and know. I am just not in their tribe.

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