Load Testing

Load Testing Overview

Ensuring that software and websites can handle real-world user demands is a critical aspect of any development project. Load testing, a key subset of performance testing, assesses how applications perform under varying levels of user activity—ranging from normal traffic to peak loads and even stress scenarios to identify breaking points. While development teams often prioritize functionality, they may neglect the user experience under heavy load or high-pressure conditions. Integrating load testing into the development process helps guarantee seamless performance and reliability, delivering a smoother experience for end users while preparing applications to thrive under real-world conditions.

If you’re new to load testing or looking to run your first load test, this page will help you get started. In this educational guide, we will break down what it is, why it’s important, how to perform a load test, and much more!

What is Load Testing?

Load testing is the practice of simulating real-world usage, or load, on any software, website, web application, API, or system to analyze and identify factors such responsiveness, degradation, and scalability.

Some examples of load testing that you might test for are: multiple users browsing and purchasing items simultaneously during a sale, users trying to download a large number of files, or simulating users logging in at the same time after a major update. 

Furthermore, load testing can simulate real-world traffic scenarios on your sites, applications, and systems. Load tests enable your teams to measure response times, throughput rates, and resource-utilization levels to identify your application’s breaking or failure point, assuming it occurs below the peak load condition. By using a load testing tool to gain insight into these metrics, it can help answer some of the following questions:

• • • What is the breaking point? When will I run out of resources?
    • How will the number of users affect performance?
    • How many simultaneous users can my website, application, or system handle?
    • Where are the bottlenecks?
    • How many transactions can we handle over a specific period?
    • Is its performance good enough?

Why is Load Testing Important?

Every day, more and more people are using your web applications, so it’s crucial to make sure they perform smoothly. Load testing is your way of making sure your app can handle the real-world traffic it might face. It helps prevent crashes, slowdowns, and frustrated users. By simulating actual user traffic, load testing allows you to find out where your app might break under pressure and fix those issues before they affect your customers. The earlier you spot and fix performance problems, the less time and money it costs you in the long run.

The cost of overlooking performance issues can be a lot bigger than you might think. In fact, a study by CISQ found that poor software quality cost the U.S. economy $2.08 trillion in 2020 alone. As more businesses go digital, those numbers are only going to rise. Bugs and glitches in your software can lead to costly problems like cyberattacks, data breaches, and financial theft, which can hurt your business. Load testing helps you catch those issues early, so you’re not pushing out a poor-performing app or website.

Poor performing sites and applications can have a negative impact and even a few seconds of downtime can significantly impact a company’s bottom line. The average cost of downtime is $5,600 per minute, according to a study by Gartner. And in March 2019, a 14-hour outage cost Facebook an estimated $90 million. The estimated cost of downtime can range anywhere from $100,000 per hour to over $540,000 per hour depending on the business. Another example would be Target and their website on Black Friday in 2019. They had an outage that was caused by not being able to handle the surge in traffic which also lead to lost sales and a tarnished customer experience. Incidents and poor application performance are the financial grim reapers and can be toxic to your customer trust and loyalty.

Avoiding any sort of downtime for you and your customers is essential to any business. With the help of load testing tools to load test, you can ensure that your website or application is ready to handle your users.

Load Testing Techniques

• Stress Testing – Stress testing is a technique that tests your system under extreme loads to see at what point it will fail or degrade. This helps to identify your system’s breaking point.
• Spike Testing – Spike testing is the process that evaluates your system’s performance when there is a sudden or sharp increase in load. This method tests your system’s ability to respond to unexpected traffic surges and ensures it remains stable during abrupt usage spikes.
• Endurance Testing (Soak Testing) – Endurance testing is the process of testing your system under a significant load over an extended period. This helps uncover long-term issues like memory leaks, database locking, or other problems that typically only surface after extended periods of usage.
• Baseline Testing – Baseline testing is the type of testing that is used to establish your performance benchmark for your system under a typical load. It’s crucial for comparison against future test results and monitoring performance deviations.
• Isolation Testing – Isolation testing is when you focus on identifying performance issues by isolating different components of your system. This helps pinpoint any specific case of performance degradation.
• Concurrency Testing – Concurrency testing is when you evaluate a system’s ability to handle multiple users or processes that are accessing it simultaneously. This helps to identify potential bottlenecks related to concurrent access such as database locking or connection limits.
• Configuration Testing – Involves running load tests across different hardware or software configurations to determine how changes in infrastructure affect system performance. This includes testing things such as memory size, server type, or different versions of software. This helps identify the optimal setup for peak performance.

Load Testing vs. Stress Testing

Both load and stress testing fall under the category of performance testing. Load testing determines how your website or application behaves during normal and peak load conditions. It ensures that the function you’re testing can handle the load that it was designed to handle. Stress testing determines how your website or application behaves beyond normal and peak conditions by overloading your website or application until it breaks or crashes. With stress testing, you’re purposely trying to induce a failure in your system so that you can find the breaking point and see how your system responds. Load testing, however, is performed to test the user actions that you would encounter daily with normal conditions. Analyzing the results of stress testing allows you to prepare for the unexpected whereas analyzing the results of load testing allows you to optimize your website or application to ensure you have a solid digital performance.

How to Start Load Testing

To get started with creating and performing load tests, you’ll first need to identify the scope of your website application objectives and select a load testing tool that is best suited for you. In the past, load testing was carried out towards the completion of a development project, and it took an incredible amount of skill and time to know how to load test. With LoadView, you can easily start load testing without sacrificing quality and get precise results to start optimizing and improving your website or application. Let’s take a look into the steps you should follow to start load testing:

1. Identify Business Goals and Objectives – It’s important to gather your requirements and identify the scope of what you’re planning on testing. For instance, are you aiming to enhance your response times, throughput rates, and resource utilization levels? Perhaps you’re also interested in determining your maximum user load. Consider identifying the key functionalities that are critical for testing to gather this information.
2. Define Your User Journeys – This step is important because you want to map out how your users will interact or navigate through your web application. When you setup and run your tests, you want to test to simulate the exact steps that your users will go through. You’ll want to you use any APM metrics to help map the step-by-step journey that your users take while using your application.
3. Setup a Control – You’ll want to define a certain control so that when you perform your load testing, you can test against your control. When you do this, you can understand how your website or application deviates from the control and optimize it accordingly.
4. Automate and Iterate – Set up load tests to be scheduled as your business scales to ensure your website and applications are running smoothly. It’s also important to weave your load testing efforts early into your development process as well.
5. Select Load Testing Tool – Don’t forget to choose a load testing tool that is easy to use, scalable, and provides precise reporting. If you’re looking for a load testing tool, LoadView provides an intuitive solution that offers load testing for plenty of scenarios, uses real browsers to simulate your real users, 40+ geo locations to simulate user access globally, and state of the art reporting to diagnose your incidents.

These steps will help you get started with load testing.

Load Testing Best Practices

• Understand and Recreate Your User Experience – Customer satisfaction is critical for the success of your business. Create load tests with realistic tests scenarios that your users would perform. This includes testing across multiple browsers and mobile devices. The more that you can ensure your website or application performs well, the more likely your users will revisit or reuse your website or application.

 

• Determine Your Metrics – There is no standard checklist of metrics, as it will depend on the application, mix of technologies used, and environment. However, some common criteria include user-perceived response time, response time specific to geographic regions, resource utilization (CPU, memory, disk, bandwidth), error count, maximum user capacity, and other business performance metrics.

  Track tail latency (p99/p99.9), error rate, saturation, and error-budget burn. Correlate results with traces via OpenTelemetry so you can jump from a slow transaction in the report to the exact span in your APM.

 

• Design Your Load Test with Existing Data – When designing your load test, you’ll want to engage other internal departments such as your IT or Marketing teams to collect historical testing data. This can be helpful to get data such as the number of concurrent users, peak sessions in a given hour, or even page views. Using this data will help you understand how you’ll want to set up your load test to ensure your load test is accurate and resembles your website and application user usage.

 

• Test Early and Regularly – Make load testing a part of the agile development process. In the past, performance testing was typically done at the end of a development project. However, in today’s age, it’s important to start the feedback loop early in the software development lifecycle to find and fix issues quickly. Start prioritizing your performance testing efforts (load testing specifically) for your agile and CI/CD process.

How to Choose a Load Testing Tool

Once you’re ready to start load testing, you may ask yourself, “How do I select a load testing tool?” Choosing a load testing tool doesn’t have to be complicated and finding a tool that can support your team’s needs is essential. At minimum, you should choose a tool that helps determine if your website or application stands up in real-world conditions (all of the best load testing tools do this). There are plenty of options in the market but when you’re evaluating a load testing tool, you should ask yourself the following questions and criteria:

1. 1. Usability – Does the tool require complex setup and is it easy to use?
   2. Accurate – Does it support real browsers across different browsers and devices?
   3. Scalability – Can it simulate global users and increase or decrease the number of concurrent users or sessions?
   4. Integrations – Can you integrate with tools you’re using day-to-day?
   5. Support – Does the tool offer a dedicated support channel?
   6. Serverless & Edge Support – Does it offer the ability to test FaaS endpoints, cold starts, and CDN/edge worker flows?
   7. Observability & Export – Does it have native integrations or OTel export for traces/metrics?

Common tools include JMeter, k6, and newer frameworks that simulate browser behavior such as Playwright load testing for end-to-end performance validation.

If you’re searching for a load testing tool that ticks all the boxes, LoadView’s solution ensures your load testing strategy remains straightforward and hassle-free. LoadView is an on-demand, cloud-based load testing platform that simplifies the load testing process and helps your teams diagnose and resolve incidents faster. It simplifies the load testing process and you can try LoadView for free today!

How Teams Run Load Tests in 2025 (Quick Start)

Load testing in 2025 isn’t just about hammering endpoints—it’s about operational discipline. Teams now treat load as part of the release pipeline, where results automatically feed back into performance budgets and service-level objectives. The workflow blends analytics, automation, and observability to validate how systems behave under real conditions before any code reaches production.

1. Define SLIs, SLOs, and Thresholds.

Start with measurable service-level indicators: response time, error rate, throughput, and saturation. Set explicit SLOs and fail conditions—especially at the p95 and p99 percentiles—to capture tail latency where user experience actually degrades. These metrics define success long before the test begins.

2. Model User Journeys from Analytics.

Build test scenarios from actual traffic patterns, not guesses. Use analytics, access logs, or APM traces to understand which pages, APIs, or workflows dominate your load profile. Model concurrency, think time, and ramp curves to mirror organic behavior.

3. Use Hybrid Runs.

Modern tests combine protocol-level virtual users for scale with a small browser cohort for user experience validation. The protocol layer generates high concurrency cheaply, while browser sessions measure rendering, layout shifts, and interactive delays that synthetic APIs alone can’t see. Together, they represent both server stress and end-user perception.

4. Gate Releases in CI/CD.

Integrate load tests into your CI/CD workflow as performance gates. Automate thresholds—builds that exceed error rates or latency budgets fail before deployment. This “shift-left” enforcement keeps regressions from reaching production and turns load testing into a continuous quality signal.

5. Analyze Traces and Iterate.

Correlate test results with distributed traces and infrastructure telemetry. Use OpenTelemetry or APM tools to link slow transactions back to specific spans, services, or queries. Feed insights into optimization cycles, rerun targeted scenarios, and measure improvement. Load testing becomes an iterative feedback loop, not a one-time event.

In 2025, the best-performing teams no longer treat load testing as an external audit—they embed it directly into engineering practice. When thresholds, analytics, and observability converge inside the pipeline, performance stops being a surprise. It becomes a measurable, predictable part of every release.