Software performance testing: types, best practises, tools

We’ll introduce you to performance testing basics – types, tools and recommendations for better performance of your applications.

Why is performance testing so important?

You’ve probably already experienced how two seemingly similar websites or apps can work completely differently. While one page loads in a flash, the other takes an infinitely long time to load. One app runs smoothly, while the other freezes, crashes, or is significantly slower. These differences are most often the cause of different software performance.

Software performance is a kind of invisible force in the digital world, responsible for ensuring that your favourite e-commerce sites can handle the onslaught of big sales events like Black Friday without crashing. Performance testing is therefore crucial to maintain the long-term viability and success of any software solution. In this article, we take a closer look at the reasons why this is so important.

Types of performance testing

First, a hypothetical example. Let’s say you develop and operate a website for online airline ticket booking. Your goal is to ensure that the site works reliably and quickly, even when a large number of users log in at once, for example during the summer holidays when demand for tickets is high.

There are a few main types of performance testing that could help you ensure that your flight booking website is able to maintain reliability and speed during periods of increased demand, such as the summer holidays, but especially in the long term.

Illustration of performance testing types

1. Load Testing

Load testing focuses on verifying how well a system can handle a certain number of users or load. This will help you identify the boundaries at which your software stops working well.

  • Your goal in load testing will be to see how your website handles normal daily load during most of the year when demand for tickets is stable. You will simulate different types of users searching for and booking flights.
  • This way, you can make sure that the site maintains reliability and speed under a typical load profile.

2. Stress Testing

Stress testing focuses on testing software under extreme conditions where the application is subjected to excessive load or unexpected situations. The aim of stress testing is to find out how the system behaves under maximum load and what its limits and tolerance boundaries are.

  • Stress testing will simulate situations where a large number of users access your site at once, for example during the summer holidays when the demand for tickets is significantly higher.
  • The aim of this testing will be to identify boundaries and problem areas such as long response times or unavailability of the site in case of excessive load.

Load testing vs Stress testing

Illustration of the difference between load testing and stress testing

3. Endurance Testing

Endurance testing focuses on how your application behaves under long-term load. The idea is to see if your website can maintain stable performance over longer periods, for example over the summer holidays when demand for airline tickets is consistently high.

  • With this type of testing, you can simulate a steady flow of users on your site over a period of days or weeks. The goal is to see if there are problems such as memory leaks that could lead to the site slowing down or crashing after prolonged use.


Illustration of endurance test

4. Spike Testing

Spike testing is designed to test your system’s response to unexpected and sudden increases in load. For example, you might run a large promotional campaign and have a large number of users logging on to your site at once.

  • In this test, you’ll want to see how quickly your system can adapt to sudden increases in demand and whether it can maintain performance during short-term spikes in user numbers.

Illustration of the spike test

5. Scalability Testing

Scalability testing focuses on how well your system is able to adapt to a growing number of requirements. This includes the application’s ability to handle an increase in the number of users, transactions, or even an increase in data volumes.

  • In the case of your website, you could test how the system behaves when you gradually increase the number of simultaneously connected users or the amount of data the application has to process. The goal is to see to what extent your system can scale up without performance degradation.

6. Volume Testing

In volume testing, you focus on how your system handles large amounts of data. This test does not focus only on the number of users, but rather on the amount of data generated in the system, such as the number of bookings, searches or transactions.

  • In this scenario, you can simulate a huge number of ticket bookings and see how your site processes and stores this data. The goal is to verify that your system can efficiently process and store large amounts of data without impacting performance or reliability.

Together, these different types of performance testing form a set of tools and approaches that allow you to achieve a higher level of reliability and performance for your website. In the context of flight bookings, it is crucial to ensure that users have access to a fast and reliable system not only in normal situations but also in more demanding ones such as the summer holiday period.

Performance testing basics – where to start?

● Requirements recognition

Before you start testing, it’s crucial to identify the performance requirements. How fast should your software respond? What is the maximum number of users that should be able to use your service at the same time?

● Choosing the right tools

There are many performance testing tools on the market, from open-source to commercial. Try to consider factors such as budget, needs and your team’s capabilities when choosing the right tool.

● Defining test scenarios

Which parts of your software are critical and need the most attention? Find them and build test scenarios that examine these parts in detail.

How to do it?

● Preparation of the environment

To make your test effective, you need to prepare an environment that is as close as possible to the real-world use of your software. Don’t forget to configure databases, servers and networks.

● Running and monitoring tests

When you’re ready, run the tests and monitor them in real time. Observe metrics such as response time, throughput and error rate.

● Analysis and interpretation of results

When the tests are completed, it is time to analyse them in detail. Identify problems and find out which parts of your code need improvement.

Performance testing best practices

Set clear goals

Be clear about your goals and the purpose of performance testing. Figure out what you want to achieve, whether it’s improving response times, managing multiple concurrent users, or identifying bottlenecks.

Start early

Include performance testing in your development cycle from the beginning, not after the fact. This will help you identify and fix problems early, saving you time and resources.

Realistic test environment

Make sure your test environment resembles the production environment as much as possible, including hardware, software and network configuration.

Identify critical scenarios

Prioritize the critical scenarios and user transactions that have the biggest impact on your application’s performance. Focus on what’s most important to your users.

Model the load

Create realistic workload models that simulate expected user behavior and traffic patterns. This will help you simulate real-world conditions and provide meaningful results.

Use the right data

Use production-like data for testing to ensure realistic scenarios. Mask sensitive data where necessary to comply with privacy requirements.

Monitor and measure

Use monitoring tools to continuously collect performance data during tests. Analyze metrics such as response times, throughput, and percentage of errors to identify problems.

Performance testing tools

Here are some performance testing tools you can use:

  1. Apache JMeter: a free open-source tool that allows you to create and run tests for various kinds of applications, including websites, web services, databases, and more.
  2. LoadRunner: a commercial tool from Micro Focus that specializes in performance testing and can handle a variety of load scenarios.
  3. Gatling: an open-source tool designed for creating and executing tests on web applications. It is written in Scala.
  4. Locust: Another open-source tool that is designed to create stress tests using simple Python scripting.
  5. BlazeMeter: a commercial tool that allows you to create, execute and analyze performance tests in a cloud environment. It has strong integration capabilities with various tools and frameworks.
  6. WebLOAD: Another commercial performance testing tool that specializes in load testing and examining the performance of web applications.


Performance testing isn’t just a tick-box exercise, it’s a critical part of software development that can save you a lot of trouble in the future. Remember, an investment in quality performance testing is an investment in the long-term satisfaction of your users and your business.

If you speak German and are an IT tester, take a look at our employee benefits and apply for our job offers.

About the author

Katarína Kučáková

Software Test Engineer

Moja cesta k testovaniu softvéru sa začala v roku 2019 až po štúdiu ekonómie a pracovných skúsenostiach v iných odvetviach. To mi pomohlo vnímať IT svet v rôznych súvislostiach. Ten totiž ponúka neustále nové výzvy, pre ktoré rada hľadám riešenia. Obľubujem oddych pri čítaní, turistiku alebo lyžovanie. LinkedIn

Let us know about you