Tutorials UPDATED: 20 February 2024

Measuring Performance: What to Consider Before Testing and Optimization

Christos Paloukas

4 min read

Before conducting performance testing on a website, several factors should be taken into consideration to ensure that the tests are relevant, accurate, and effective in identifying and addressing performance issues.

Here we will cover the key factors to consider before initiating performance testing and optimization on a website, including defining objectives, choosing appropriate tools, creating a testing environment, and executing baseline tests.

Define Objectives

The first step in preparing for performance testing is to clearly define the objectives of the tests as best as possible. As described in our article on what performance testing is, it is essential to make yourself more aware of the metrics collected from various types of testing. This will help you better understand what you need to focus on to optimize your site’s performance.

Objectives may include optimizing homepage load times and script efficiency for mobile devices, to improve user experience. For load testing, objectives may focus more on server response times. For example, they may focus on the checkout process of an e-shop under high-load conditions to ensure the website can handle the expected workload. 

By establishing clear objectives, the performance testing process can target the most relevant aspects of the website and provide actionable insights and results. Understandably, what you need to do to improve the performance of a website may not be clear at first. The initial baseline tests that we refer to in a later step will help mould the final objectives.

Choose Appropriate Tools

Selecting the right tools for performance testing is the next step. The selection should be based on factors such as the objectives set.

For instance, if a major objective of the testing is improving homepage load time metrics for mobile users, then you would select a tool capable of gathering those metrics. That would be the browser-based, or front-end, performance tool PageSpeed Insights (PSI).

The use of multiple tools may be required to fulfil your objectives. The ease of use is a major consideration when selecting proper tools. This, of course, depends on the expertise of the person or team executing the tests. In the case of large-scale load testing, you may need to review the testing budget before testing as well. That’s because large-scale load testing may get costly.

Create a Testing Environment

Before conducting performance testing, it would be wise that you create a testing or staging environment that accurately replicates the production environment. This ensures that the tests are conducted in a controlled and isolated setting. This way you protect the live website from any impact while still providing accurate results.

The testing or staging environment should include all relevant components and configurations of the website and hosting solution, such as:

  • webserver and database configuration,
  • caching configuration,
  • site files,
  • databases, and,
  • content delivery networks (CDNs)

should be configured to resemble the production environment as closely as possible in terms of hardware, software, and network configurations. You may skip this step in gathering initial baseline test results or viewing live user data collected using a tool like PageSpeed Insights.

However, a testing environment will be necessary for making changes to the website and testing those changes without interfering with the production website.

Execute and Evaluate Baseline Tests

The last step before any performance testing on a website is to execute initial tests and establish baseline performance metrics. 

Repeated trials of the initial tests should be executed as a best practice, in an attempt to eliminate variations or errors that may occur during the testing process. The results from back-to-back tests executed using GTmetrixs or PageSpeed Insights may vary due to several factors, like network conditions and server response time. It is generally recommended to test a website multiple times from different locations and at different times. This way, you get a better overall baseline of website performance.

After executing and evaluating baseline tests, your test objectives may change based on the baseline test results.


We delved into the factors to address before engaging in performance testing and optimization. We talked about how you should define clear objectives, select appropriate tools aligned with your goals, create a controlled testing environment, and execute baseline tests for accurate insights. This strategic approach ensures effective identification and resolution of performance issues while optimizing your website for an enhanced user experience.

Shortly, we will resume the performance-measuring journey by taking a closer look at the performance tools. In the 3rd part of this series, we will study an example of performance analysis using the PageSpeed Insights (PSI) reports.

Stay tuned!

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