Website Speed Test: Top Tools and Testing Techniques

What is Website Speed Testing?

Defining Website Speed Testing

Website speed testing measures how quickly your website loads for users. It involves tools that simulate user interactions and analyze performance metrics. Website speed testing tools measure multiple aspects of loading, such as server response time, content load time, and total page rendering. These tools provide a holistic view of the website’s speed and help pinpoint specific issues causing delays.

By simulating a user’s experience, website speed testing enables developers to detect the impact of different factors such as image size, script performance, and server configuration. These tools help identify areas to improve speed and enhance user experience, making it easier to understand and implement changes that optimize overall performance.

Why Website Speed Testing is Important

Website speed affects user experience, search rankings, and conversion rates. Faster websites provide better user satisfaction, which boosts engagement and reduces bounce rates. If a website loads too slowly, users may abandon it, leading to missed opportunities and reduced customer retention.

Google also ranks fast websites higher, improving search engine results visibility. Higher search rankings mean more traffic, leading to increased potential customers. A quicker site increases conversions, directly impacting revenue. Every second that there is a delay can significantly decrease conversion rates, affecting a company’s bottom line. Faster websites also provide an edge over competitors with slower sites, leading to increased customer loyalty and brand preference.

Understanding Core Web Vitals for Website Speed Test

What Are Core Web Vitals?

Core Web Vitals are vital metrics that evaluate user experience. These include Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). Google uses these metrics to determine a website’s page experience quality. They focus on the loading experience, interactivity, and visual stability aspects.

Core Web Vitals help developers identify and fix issues that impact user experience by assessing these factors. Meeting Core Web Vitals standards helps improve rankings, as Google prioritizes sites that provide a positive user experience.

Largest Contentful Paint (LCP)

This element measures the time the largest visible element takes to load. It reflects perceived loading speed and how quickly the main content becomes visible to users. Slow servers, large images, and render-blocking scripts can affect LCP. Large unoptimized images and heavy CSS can significantly increase LCP, resulting in poor user experience.

Optimizing images using modern formats like WebP, reducing server response times, and using efficient caching improve LCP. Content Delivery Networks (CDNs) also help deliver content more quickly by storing copies closer to users, thereby reducing loading time.

First Input Delay (FID)

This metric tracks the time between a user’s initial interaction with a webpage and the browser’s response. It reflects page responsiveness and measures how interactive the page feels to users. Factors like heavy JavaScript, which blocks the main thread, can increase FID, leading to user frustration.

Minimizing JavaScript and deferring non-essential scripts can help improve FID. Developers can make pages more responsive by breaking up large JavaScript files and reducing the work done on the main thread. Ensuring tasks run efficiently without blocking user interactions is critical to achieving good FID scores.

Cumulative Layout Shift (CLS)

CLS measures unexpected layout shifts during page loading. It affects visual stability and can frustrate users if elements move around while loading. Causes include images without dimensions and dynamically injected content. When images, ads, or fonts load unpredictably, it can result in poor user experience.

Adding size attributes to media, setting fallback fonts, and avoiding content shifts can reduce CLS. Reserve space for dynamic content and preload important assets to prevent layout shifts. Predictable layouts make it easier for users to interact with your website, improving overall satisfaction.

Time to First Byte (TTFB) in Website Speed Tests

What is TTFB?

The Time to First Byte (TTFB) metric tracks the time for the first byte of data to reach the user’s browser. It indicates server responsiveness and how quickly the server can handle a request. The shorter the TTFB, the faster the server is in delivering information. TTFB helps diagnose slow server response issues that can affect the rest of the page-loading process.

Why Slow TTFB Matters?

Slow TTFB negatively impacts overall page load times and user experience. A delayed server response means users wait longer to see any content, which can lead to frustration and site abandonment. Search engines like Google also consider TTFB when ranking pages, meaning slow TTFB can harm your SEO efforts. Furthermore, slow TTFB can create a cascading effect, slowing down the rest of the page-loading process, including images, scripts, and other resources.

Factors Affecting TTFB

Several factors affect TTFB, including server response times, network latency, and inefficient database queries. Server configuration, caching, and the hosting environment can all play significant roles. Network latency, especially for users accessing a site from distant locations, can increase TTFB. Slow database queries and inefficient server-side processing can also significantly affect response times. Optimizing these factors helps improve overall performance.

How to Optimize TTFB

To optimize TTFB, reduce server response time by improving hardware and software. Utilize Content Delivery Networks (CDNs) to reduce latency and ensure that content is delivered efficiently to users regardless of location. Optimize server-side scripts and databases to minimize processing delays. Enabling caching allows frequently accessed content to be stored and retrieved more quickly. Using faster DNS resolvers and improving backend infrastructure can significantly impact TTFB.

Synthetic Website Speed Test vs. Real User Monitoring (RUM)

What is a Synthetic Website Speed Test?

A synthetic website speed test uses predefined environments to measure performance. It simulates user behavior under controlled conditions, providing consistent, repeatable results. Synthetic tests help establish benchmarks and identify issues without depending on real-time user data. Unlike real user interactions, these tests are scripted and conducted in a controlled environment, hence the term “synthetic.”

These tests are great for comparing site performance before and after changes or releases. They help detect bottlenecks and ensure that updates lead to measurable improvements in speed.

The Importance of Controlled Environments

The beauty of such tests lies in their ability to manipulate or emulate various conditions. Network speed, browser type, geographical location, and device type can all be adjusted to see how your website performs under different circumstances. This controlled environment provides a consistent basis for testing and comparison.

Benefits of Synthetic Website Speed Testing

Synthetic testing helps identify potential issues before they affect real users. It provides website details like load times, content rendering, and script execution. By creating a controlled testing environment, synthetic tests offer consistent data, making it easier to compare results over time. This controlled environment eliminates external factors, ensuring that any detected performance issues are related to the website and not external conditions.

How Synthetic Website Speed Tests Provide Performance Metrics

One of the primary benefits of a synthetic test is the detailed performance metrics it provides. Metrics such as time to first byte – TTFB, page load time, and render time are all measured during the test. These metrics can help identify areas where your website’s performance could be improved.

Benchmarking and Comparison

Synthetic tests offer a reliable way to benchmark your website’s performance over time. Because the tests are conducted in a controlled environment, you can compare your website’s performance against previous tests or even against competitors’ websites. This comparison can help you identify where you stand and what you need to improve.

Proactive Monitoring with Synthetic Website Speed Tests

Another advantage of synthetic tests is their ability to provide proactive monitoring. These tests can be run regularly, even when no users are on your site. This action lets you catch potential issues before they affect real users, ensuring a smooth and enjoyable user experience.

Limitations of Synthetic Testing

Synthetic tests can’t fully capture real user experiences. Variability in real-world network conditions, user devices, and browsing behaviors make synthetic tests less reflective of actual user experiences. Real users interact with websites in unpredictable ways, and their experience can be affected by factors such as poor connectivity and outdated devices. Synthetic tests do not account for such variability, which is why RUM is essential for a complete picture.

What is Real User Monitoring (RUM)?

RUM collects data from real visitors to understand actual user experiences. It provides insights into performance across different devices, networks, and regions. RUM highlights issues that users are experiencing, giving a true sense of how the website performs in real-world conditions. This real-time monitoring allows developers to understand the issues impacting users and make changes that benefit the entire user base.

Cloudflare RUM Tool

Cloudflare offers RUM tools to collect data from actual users. Cloudflare’s RUM tool helps identify region-specific issues and device-related performance drops and pinpoint areas that can benefit from optimization. This requires adding a JavaScript code/file to your site, which may slightly slow it down. An HTTP request will be added, and execution time will also rise.

Techniques for Website Speed Testing

Comprehensive Testing Across the Website

Test different sections of your website, not just the home page. Include product pages, blog posts, and landing pages for a complete view of website performance. Different sections of your site may load differently, and performance issues may vary based on content type or complexity. Testing multiple pages helps fully understand how various areas perform, ensuring no bottlenecks or high-load components are overlooked.

Geographical Considerations in Testing

Test your website from multiple locations worldwide to understand regional performance. The physical distance between the users and the server they are trying to reach impacts load times due to latency. Using CDNs helps reduce latency and improve load times globally by distributing content closer to users. Conducting tests from various locations also helps identify server placement and network performance issues, leading to better content delivery strategies.

Device Emulation in Speed Testing

Test your site on multiple devices: desktops, iPhones, and Android devices. Device-specific testing helps identify and fix issues that affect different users. Mobile devices often have different processing power and network conditions compared to desktops. By emulating various devices, you can optimize visitor user experience, ensuring pages are responsive, elements render correctly, and the site remains accessible regardless of device type.

Conducting Multiple Test Rounds

Run several test rounds for accurate results. Averaging multiple test results provides a clearer picture of overall performance and helps detect anomalies. Single tests may not accurately reflect performance due to variability in server response or temporary network issues. You can better understand trends and establish a reliable baseline for the website’s speed by conducting multiple tests.

Using Multiple Website Speed Test Tools

Using different tools provides a broader range of insights. Each tool may focus on various aspects of speed, offering a more comprehensive view of potential issues. Some tools may emphasize metrics like Core Web Vitals, while others focus on server response or visual elements. Combining the insights from multiple tools ensures that all performance aspects are examined, allowing for more targeted optimization efforts.

Below, I list various tools you can use to conduct your website speed test.

Understanding Website Speed Test Scores

Website Speed Test Scores Explained

Website speed test tools assign a score based on various metrics. These scores help you assess overall website performance and identify areas to optimize. Speed test scores provide an at-a-glance understanding of your site’s performance against benchmarks. The scores are calculated from a combination of metrics like LCP, FID, CLS, and TTFB. Understanding these scores helps developers prioritize which optimizations will have the most significant impact on the user experience.

Tips on Improving Your Speed Test Score

Each website speed testing tool provides a list of actionable tips to improve your score. These tips are based on analyzing the specific metrics that affect your site’s performance, such as unoptimized images, render-blocking resources, or large JavaScript files. You can improve your website’s speed by fixing suggested items.

Waterfall Analysis in Website Speed Tests

What is a Waterfall Chart?

A Waterfall chart displays how each HTTP request loads, highlighting bottlenecks. It helps visualize the sequence and timing of resource loading on a webpage. The chart shows each request’s duration, from the initial connection to the download time. Waterfall charts are valuable for identifying elements that delay page load, such as large files, redirects, or third-party scripts.

Using Waterfall Analysis to Optimize Performance

Identify slow-loading requests and reduce HTTP requests using Waterfall charts. Combine files, enable caching, and prioritize essential resources to improve load times. You can target and eliminate bottlenecks by understanding which requests take the most time. Reducing the number of HTTP requests through file concatenation and caching makes pages load faster, resulting in better speed test scores and improved user experience.

Importance of Using the Right Canonical Domain in Testing

Correct Domain Settings for Accurate Speed Testing

Use the correct canonical domain version when testing. Test using the version set in your hosting and DNS settings to avoid redirects and misleading results. Testing with the incorrect version of your domain can add unnecessary redirects, leading to inflated load times during testing. Testing the correct canonical version ensures that results accurately reflect end users’ experience.

Impact of Improper Domain Use on Test Results

Testing with an incorrect domain version leads to unnecessary redirects, affecting test scores. Consistent domain settings improve accuracy in speed tests. Redirects add delays to page loading, negatively impacting performance scores and providing misleading data. To get a clear and accurate view of your website’s performance, ensure that you use the version of the domain that users will interact with.

Practical Example

When performing a website speed test, it’s crucial to use your final canonical domain, including ‘HTTPS’ and ‘www’ (if you set your domain to use ‘www,’ if not, then you can skip the ‘www’ part), like:

https://www.yourdomain.com

If you perform test on URL with “http://” instead of “https://”

http://www.yourdomain.com

you’ll be redirected to the “https://” version

https://www.yourdomain.com

The above is a standard redirection process when your primary site enforces HTTPS (SSL / TLS enabled), and you’ve chosen to use ‘www.’ with your domain.

If you perform a website speed test on a naked domain

yourdomain.com

By default, it will be used in the test as

http://yourdomain.com

and you’ll be redirected twice: once to

https://yourdomain.com

and second to

https://www.yourdomain.com

Each such redirection will lower your score in site speed performance testing. However, in real-life scenarios, when a user navigates to ‘yourdomain.com,’ these redirects happen only the first time they enter your site and only if the user navigates to your ‘naked domain.’ The rest of the traffic for that user on the site will already include https://www.yourdomain.com/<pages> in its URLs.

The above is what truly matters. Google indexes your webpage with the default specifications, meaning that it will include the ‘https://’ and ‘www’ in the URL (if that is what was set in DNS and hosting configuration), and the user will navigate to the entire URL from SERPs. The default canonical domain URL matters to Google, not the first-time redirect. Therefore, conducting a website speed test using the default canonical domain URL usage and not the naked domain is essential.

Use the HTTPS Status code tool to find your default canonical domain URL.

Popular Website Speed Test Tools

GTmetrix

Probably the most popular tool for site speed testing, GTmetrix provides detailed performance insights. It measures load times, identifies bottlenecks, and offers suggestions for improvements. GTmetrix provides a summary score and a detailed breakdown of various metrics, helping users understand specific issues impacting speed. Use GTmetrix to evaluate particular page elements and loading behavior and follow the recommendations to boost overall site performance.

While registering a free account on GTmetrix, you can get more features, like custom browser settings and extended geolocations. After registration, you must enter your account settings and validate your email on the “Your Plan” page, or you will not get additional On-Demand tests.

After registration, on the test starting page in [Analysis Options], you can enable the “Adblock Plus” option. Adblock Plus browser extension is known for blocking specific JavaScript files. So, when you perform a website speed test on a URL, you can set this option to see how it affects your site. After that, check the [Waterfall] tab to see if any files were skipped because of Adblock.

In a paid account, you can schedule tests. For example, you can schedule for once a week, and if scores differ between tests, you will need to investigate what happened.

WebPageTest

WebPageTest provides advanced features for in-depth analysis. It allows you to run tests from different locations and devices, giving you a detailed report about the website’s performance. This tool is handy for understanding how a site performs for users in various locations and under different network conditions.

Pingdom

Pingdom monitors and measures your website’s performance. It provides a simple way to understand load times and identifies issues that need fixing. Use it alongside other tools for better results. Pingdom focuses on real-world performance and highlights areas for improvement. Combining Pingdom results with different tools, you can better understand how well their website performs.

Google PageSpeed Insights

Google PageSpeed Insights assesses your website for both mobile and desktop performance. It provides recommendations to optimize load speed, making it a valuable tool for improving user experience. The tool also includes Core Web Vitals metrics critical to higher search engine rankings.

Less Popular but Useful Website Speed Test Tools

GiftOfSpeed

GiftOfSpeed offers a full-page speed test and compression testing. Like the popular tools above, it performs a full-scale analysis with a comprehensive list of actionable improvement tips.

They also have separate GZip and Brotli compression testing that helps ensure efficient delivery of resources. By evaluating compression, GiftOfSpeed allows developers to see how much improvement they can achieve by compressing text-based resources, reducing file size, and speeding up delivery.

ByteCheck

ByteCheck focuses on measuring the Time To First Byte (TTFB). It helps diagnose server-side bottlenecks that impact initial load speed. ByteCheck’s focus on server response times helps determine whether issues are related to the backend infrastructure. Identifying slow server responses helps developers make targeted improvements to enhance TTFB.

Almost all the tools that perform full-scale website speed tests also perform TTFB checks. For easier TTFB measurement, ByteCheck is a tool designed for TTFB only.

REDbot

REDbot checks HTTP headers for efficiency. It helps ensure that headers are configured correctly, improving overall site performance. Proper header configuration can enhance caching and resource delivery. REDbot allows developers to spot potential issues in HTTP headers, such as incorrect caching policies or security misconfigurations.

Website Optimization: Performance and Speed Analysis

Website Optimization provides a free tool for website performance and speed analysis. Use it with other tools for a holistic view of website speed. The tool helps evaluate metrics like TTFB, content rendering, and total load time, providing actionable recommendations to enhance website performance. A combination of different testing approaches provides a clearer picture of areas that need attention.

Using Browser Developer Tools for Website Speed Testing

Speed Testing Directly From Your Browser

All the above tools perform “synthetic tests,” meaning they’re executed in controlled environments. You can run real-world testing with your browser.

• If you use Firefox or any Chromium-based browser, like Google Chrome or Microsoft Edge Chromium, press [F12]. This key will open the Developer Tools bar.
• Click the [Network] tab, then reload your site or a specific page with [F5].
• This action will show you all the requests the browser executes to load your page fully and how long it takes for each request to receive a response. Similar to the “Waterfall” feature of the synthetic tools in the previous section.

Emulating Specific Devices for Testing

Browser developer tools let you emulate different devices. This helps identify issues specific to certain devices, such as mobile responsiveness problems. Emulating devices is handy for understanding how a site performs across various screen sizes, network conditions, and device capabilities.

• To enable device emulation in both Firefox and Chromium-based browsers, you can press
  [CTRL] + [SHIFT] + [M]
• In Chromium browsers, it will be in “Toggle device emulation” mode. In Firefox, enable “Responsive Design Mode,” which is the same.
• In the top bar menu, you can select the device’s dimensions and device type or rotate the device horizontally.

Using VPN for Location-Based Testing

VPNs allow you to simulate different geographic regions during tests. Testing from various locations helps understand global performance and identify latency issues. You can use a VPN to change your virtual location and evaluate your site’s performance in different countries. This approach helps pinpoint performance bottlenecks related to server placement and network conditions.

What Do You Do With – Turn Off Lazy Image Loading for Initial Images – Suggestion in WordPress?

Check out our article on how to Turn Off Lazy Image Loading on Initial Images through WordPress Child Theme functions.php.

Conclusion

Using both synthetic tests and RUM provides a complete view of website performance. Synthetic tests identify technical issues, while RUM captures real-world user experiences. By combining data from both methods, you can prioritize optimizations impacting user experience. However, RUM has drawbacks in adding JavaScript code to your website, making it slightly slower.

Regular speed tests help ensure consistent performance. Continuous testing helps maintain optimal load times and user satisfaction as websites change. Over time, content updates can cause a decline in performance and added plugins or server-side issues. Regular speed tests catch potential problems early, helping maintain the best user experience.

If you find any mistakes or have ideas for improvement, please follow the email on the Contact page.