Welcome!

IBM Cloud Authors: Liz McMillan, Elizabeth White, Mamoon Yunus, Pat Romanski, Kevin Benedict

Related Topics: @DevOpsSummit, Linux Containers, Containers Expo Blog

@DevOpsSummit: Blog Feed Post

The Speed Index | @DevOpsSummit @Catchpoint #DevOps #WebPerf #DX #AI

There’s a lot of buzz around the speed index metric, but what exactly is this metric and how is it calculated?

Understanding Speed Index
By Moiz Khan

There’s a lot of buzz around the speed index metric, but what exactly is this metric and how is it calculated? Even more so, why do we need a new metric when there are so many already on the plate? This article gives you detailed answers to these questions.

What is speed index?
User expectations have changed drastically, webpages are expected to load faster with all elements rendering as soon as possible; user frustration increases if the visual content of the page is slow to load.

There are several metrics used to measure user experience, but do these give us a clear enough picture? Not really. For example, render start indicates when the page started painting, but this could mean it loaded a white background, a random object, or just a dot on the page; the user, however, may still be looking at a blank page. The document complete metric, which flags the onLoad event, may not be important from an end user’s perspective as it considers below-the-fold requests as well; there could be instances where the Document complete is triggered even when the page is blank.

Speed Index is an abstract score that was introduced to overcome the limitations of the current set of metrics. It measures user experience and unlike render start or document complete, it is not a timing metric, therefore the smaller the score, the better it is. Speed index takes into account the visual completeness of the page above-the-fold. It does a much better job of measuring the perceived performance of a page, but does this mean other metrics are irrelevant? This is debatable. Instead, the choice of a metric depends on the scenario and the nature of the website being analyzed.

How relevant is speed index?
Speed index will let you know if the visible content is loading quickly or not. The lower the score, the better is the user experience, and vice versa. The speed index score indicates whether you need to optimize your page or not. To maintain a good score, there are two critical aspects that you should look at: optimizing content efficiency and optimizing the critical rendering path.

Web applications continue to grow in terms of functionality, scope, and usability; hundreds of resources make up these applications and fetching each resource adds to the page load time. Maintaining performance is possible only when the resources and content that make up the page are optimized. Speed index plays a critical role in monitoring the performance of visible content.

How is it calculated?
Speed index lets you measure how quickly a page’s content is visible. However, it can be a little tricky to understand what it means and what factors contribute to the score.

Speed index uses film strips to calculate the score, each frame is scored for visual completeness above the fold – the score is 0% for a blank screen and 100% for a visually complete screen. The score for each frame is calculated using this formula:

interval time*(1 – visual complete %/100)

The process is repeated for every frame and the cumulative of all the scores gives you the speed index of that page.

Let’s take an example:

Adding all of the scores gives the speed index score:

500 + 450 + 350 + 200 + 50 = 1550

Here is another example:

Let’s add up the score:

500 + 500 + 475 + 400 + 350 = 2225

From a performance point of view, the lower the score the better it is. There is no defined benchmark for speed index, however, a score of <1000 is considered good. User experience is better if above-the-fold content is displayed faster, and this is what speed index determines.

Measuring speed index using Catchpoint
To check speed index, you will need to enable the “Capture Filmstrip” option under Advanced Settings of a test. It is displayed along with other metrics in the charts, and you can also view it in the waterfall graphs. Here are a few examples that illustrate how pages that load the visual content faster have a better speed index score.

Example 1:

In the above example, the page has a good speed index score of 1260. If you look at the film strip, the interval is of 500ms, and from the second frame the visual content is visible, which is about 1 second. Frame three has almost all the content loaded. From a user’s point of view, we have engaged them from the very first second due to the fact that the page is optimized.

Example 2:

In the above image, the visual is visible in the third frame. The first two frames are blank, which is why the speed index score of 1741 is higher than the first example. The user views content at 1.6 seconds, unlike the first example where the user viewed the content within a second.

Example 3:

Based on the final example above, we are able to understand what is happening. The first two frames are blank and in the third frame visual content starts to load. However, the completeness is less compared to the other two images in the same frame. The visual content continues to load in the fourth frame, but it’s not complete until the fifth frame. This means that the user needs to wait for 1.6 seconds to see something on the page, and another 2.8 seconds to view the complete visual content.

In all of the examples, the render start is triggered before the user views anything on the page. In the second example, the render start happens at 1195ms and the visible content starts to load at 1604ms. In the third example, the render start happens at 1296ms and the visible content starts to load at 1597ms. This is the uniqueness of speed index. With a highly unoptimized website, the difference could be extremely high, with render start happening quickly but the visible content loads quite late. You need these insights to optimize your websites.

Limitations of Speed Index
When running transaction tests for dynamic sites or single page applications that use ajax, the score is always good in the steps that follow once the page is opened. This is because the page does not refresh after it is loaded. Pages featuring carousels that rotate automatically may be penalized because they continue to change even after the page load is completed.

Summary
Speed index indicates the visual completeness of the page; however, it does not indicate if the content was critical or non-critical for the user. As such, it should not be a replacement for other metrics and should be considered a rather useful and much-needed addition to the list of metrics. You will still need to look at render start and document complete to understand the overall performance. Speed index gives you a different perspective of the user experience that your site delivers.

The post Understanding Speed Index appeared first on Catchpoint's Blog - Web Performance Monitoring.

More Stories By Mehdi Daoudi

Catchpoint radically transforms the way businesses manage, monitor, and test the performance of online applications. Truly understand and improve user experience with clear visibility into complex, distributed online systems.

Founded in 2008 by four DoubleClick / Google executives with a passion for speed, reliability and overall better online experiences, Catchpoint has now become the most innovative provider of web performance testing and monitoring solutions. We are a team with expertise in designing, building, operating, scaling and monitoring highly transactional Internet services used by thousands of companies and impacting the experience of millions of users. Catchpoint is funded by top-tier venture capital firm, Battery Ventures, which has invested in category leaders such as Akamai, Omniture (Adobe Systems), Optimizely, Tealium, BazaarVoice, Marketo and many more.

@ThingsExpo Stories
The question before companies today is not whether to become intelligent, it’s a question of how and how fast. The key is to adopt and deploy an intelligent application strategy while simultaneously preparing to scale that intelligence. In her session at 21st Cloud Expo, Sangeeta Chakraborty, Chief Customer Officer at Ayasdi, will provide a tactical framework to become a truly intelligent enterprise, including how to identify the right applications for AI, how to build a Center of Excellence to ...
"We're a cybersecurity firm that specializes in engineering security solutions both at the software and hardware level. Security cannot be an after-the-fact afterthought, which is what it's become," stated Richard Blech, Chief Executive Officer at Secure Channels, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Massive Networks will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Massive Networks mission is simple. To help your business operate seamlessly with fast, reliable, and secure internet and network solutions. Improve your customer's experience with outstanding connections to your cloud.
Everything run by electricity will eventually be connected to the Internet. Get ahead of the Internet of Things revolution and join Akvelon expert and IoT industry leader, Sergey Grebnov, in his session at @ThingsExpo, for an educational dive into the world of managing your home, workplace and all the devices they contain with the power of machine-based AI and intelligent Bot services for a completely streamlined experience.
Because IoT devices are deployed in mission-critical environments more than ever before, it’s increasingly imperative they be truly smart. IoT sensors simply stockpiling data isn’t useful. IoT must be artificially and naturally intelligent in order to provide more value In his session at @ThingsExpo, John Crupi, Vice President and Engineering System Architect at Greenwave Systems, will discuss how IoT artificial intelligence (AI) can be carried out via edge analytics and machine learning techn...
SYS-CON Events announced today that Datera, that offers a radically new data management architecture, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datera is transforming the traditional datacenter model through modern cloud simplicity. The technology industry is at another major inflection point. The rise of mobile, the Internet of Things, data storage and Big...
Consumers increasingly expect their electronic "things" to be connected to smart phones, tablets and the Internet. When that thing happens to be a medical device, the risks and benefits of connectivity must be carefully weighed. Once the decision is made that connecting the device is beneficial, medical device manufacturers must design their products to maintain patient safety and prevent compromised personal health information in the face of cybersecurity threats. In his session at @ThingsExpo...
In his session at @ThingsExpo, Arvind Radhakrishnen discussed how IoT offers new business models in banking and financial services organizations with the capability to revolutionize products, payments, channels, business processes and asset management built on strong architectural foundation. The following topics were covered: How IoT stands to impact various business parameters including customer experience, cost and risk management within BFS organizations.
SYS-CON Events announced today that CA Technologies has been named "Platinum Sponsor" of SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business - from apparel to energy - is being rewritten by software. From planning to development to management to security, CA creates software that fuels transformation for companies in the applic...
From 2013, NTT Communications has been providing cPaaS service, SkyWay. Its customer’s expectations for leveraging WebRTC technology are not only typical real-time communication use cases such as Web conference, remote education, but also IoT use cases such as remote camera monitoring, smart-glass, and robotic. Because of this, NTT Communications has numerous IoT business use-cases that its customers are developing on top of PaaS. WebRTC will lead IoT businesses to be more innovative and address...
An increasing number of companies are creating products that combine data with analytical capabilities. Running interactive queries on Big Data requires complex architectures to store and query data effectively, typically involving data streams, an choosing efficient file format/database and multiple independent systems that are tied together through custom-engineered pipelines. In his session at @BigDataExpo at @ThingsExpo, Tomer Levi, a senior software engineer at Intel’s Advanced Analytics ...
SYS-CON Events announced today that App2Cloud will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. App2Cloud is an online Platform, specializing in migrating legacy applications to any Cloud Providers (AWS, Azure, Google Cloud).
Recently, IoT seems emerging as a solution vehicle for data analytics on real-world scenarios from setting a room temperature setting to predicting a component failure of an aircraft. Compared with developing an application or deploying a cloud service, is an IoT solution unique? If so, how? How does a typical IoT solution architecture consist? And what are the essential components and how are they relevant to each other? How does the security play out? What are the best practices in formulating...
SYS-CON Events announced today that MobiDev, a client-oriented software development company, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. MobiDev is a software company that develops and delivers turn-key mobile apps, websites, web services, and complex software systems for startups and enterprises. Since 2009 it has grown from a small group of passionate engineers and business...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devic...
SYS-CON Events announced today that Dasher Technologies will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Dasher Technologies, Inc. ® is a premier IT solution provider that delivers expert technical resources along with trusted account executives to architect and deliver complete IT solutions and services to help our clients execute their goals, plans and objectives. Since 1999, we'v...
SYS-CON Events announced today that Ayehu will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Ayehu provides IT Process Automation & Orchestration solutions for IT and Security professionals to identify and resolve critical incidents and enable rapid containment, eradication, and recovery from cyber security breaches. Ayehu provides customers greater control over IT infrastructure throu...
SYS-CON Events announced today that Elastifile will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Elastifile Cloud File System (ECFS) is software-defined data infrastructure designed for seamless and efficient management of dynamic workloads across heterogeneous environments. Elastifile provides the architecture needed to optimize your hybrid cloud environment, by facilitating efficient...
SYS-CON Events announced today that Grape Up will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Grape Up is a software company specializing in cloud native application development and professional services related to Cloud Foundry PaaS. With five expert teams that operate in various sectors of the market across the U.S. and Europe, Grape Up works with a variety of customers from emergi...
SYS-CON Events announced today that Grape Up will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Grape Up is a software company specializing in cloud native application development and professional services related to Cloud Foundry PaaS. With five expert teams that operate in various sectors of the market across the U.S. and Europe, Grape Up works with a variety of customers from emergi...