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Quality assurance is an essential process for ensuring software’s seamless performance. As an integral part of QA, testing defines the quality of the product and helps improve it in the long run.

Neglecting load and performance testing activities can result in downtime. If your business is operating online, or you rely heavily on cloud servers to support your infrastructure, you are probably familiar with the “cost of downtime per minute” term. Even the greatest ones have paid it occasionally. For example, Amazon’s infamous “Prime day fail” included severe site outages for only about 40 minutes, but it was enough to lose about $5 million.

To avoid the same fate, it is essential to get your testing priorities straight and explore your software limits and capacities before it’s released to production. This is why the two major software testing processes we will focus on in this article are load testing and performance testing. They share some critical similarities yet are different in functionality.

What is load testing?

To ensure that a system can endure particular demands and respond to them, QA specialists employ the process of load testing when analyzing a website, mobile application, or other software solution. This part of QA operations has proven effective in facilitating and optimizing QA processes and enabling specialists to conduct quality control operations accurately. 


Load testing helps track the system’s behavior under normal and abnormal conditions and estimates an application’s maximum operating capacity. During load testing, the load placed on the software can be increased to go beyond average — such an experimental approach is called stress testing. Namely, load testing models the assumed usage of the software by simulating a large number of users who access the software simultaneously. This is why this type of testing is effective for multi-user systems. 

One of the notable features of load testing is its ability to show measurable results. Despite a common misconception, load testing can be precisely targeted and partially automated, making it very convenient for Agile-driven processes. Load testing is often applied if the system or service is subject to a service-level agreement. Thus, it is usually introduced in earlier stages of software development to fix capacity issues before they affect the software users. 


Often, load testing is performed in conjunction with performance testing. Some experts consider it a subcategory of performance testing, using the latter as an umbrella term for all performance-related testing activities. 

Read also: Why quality assurance is essential to any delivery team

Benefits of load testing 

  • Reducing the cost of failure

With the help of load testing, you can largely cut your expenditures on fixing system failure. For instance, let’s say that during load testing, you discover that your app fails to give users the required results like data or downloadable files when being loaded. Now that the bug has been detected by you and not by end users, you can stop it from marring your user’s experience. Also, even if you have the time and the resources to sort out technicalities after the release, a single bad experience sticks with a user forever. Chances are you’ll lose them — or, in the worst cases, cause damage to your brand reputation

  • Enhancing the scalability of software 

A software product can be scaled by adding resources to the system, which gives it more flexibility and provides customers with more opportunities to use it.  Poor resources utilization and When software does not handle concurrent users well, it leads to issues such as poor utilization of resources and memory leaks. Load testing enables software teams to find out the limits of their application’s operational capacity. When the team is aware of the system’s limitations, they can easily identify the changes needed to make the product more scalable.

  • Guaranteeing increased customer satisfaction

Through load testing, QA experts can ensure that the system is consistent with the required standards. Users tend to notice the tiniest, one-second delay and might feel uncomfortable using your application, especially if it handles sensitive data (like payments) or implies long-term usage. In that case, most of the users prefer to switch to a faster alternative, because seamless UI feels more secure.  Thus, customers will develop more loyalty for the company producing the software that is well-tested before production.  

  • Helping spot weak code and hidden bugs

The more complex your software is, the higher the chances that a few imperfect code lines crash the system when the load passes a certain threshold. Due to its high precision, load testing unmistakably detects system imperfections. Based on the outcome of load testing procedures, specialists can discover load bottlenecks before deployment.


Performance testing definition

There are three main measurements of a product’s performance: speed, stability, and scalability. Speed shows how quick the application’s response is. Scalability is about finding out how many users can work with the app at the same time without losing in app’s general performance and ease of use. Stability is involved in checking whether or not the product can handle load differences. 

Software performance testing aims to assess all these measurements, helping QA specialists ensure that the product’s key characteristics are compliant with the required standards. 

To conduct performance testing effectively, testers need to be familiar with proven tools such as NeoLoad, WebLOAD, Jmeter, Gatling, and LoadRunner. These tools are considered to be some of the best programs for detecting system bottlenecks. The performance testing process includes elements such as a browser, a page, server request processing time, concurrent user volumes, and other data points. 

Performance testing combines the tests showing an app’s speed, sustainability, and how robust it is. Performance testing aims to determine productivity, measure response time, improve load capability, ensure reliability and usability, and catch memory leaks before they harm the system. 

Benefits of performance testing 

Some of the benefits described below coincide with the performance testing ones above, and that’s now new — both those testing directions work towards the same goals. 

  • Validating software’s fundamental features

Your software must have a reliable foundation represented by speed, stability, and scalability —  the three key quality criteria of sound software mentioned earlier. Having a solid foundation allows you to make critical decisions about future functionality based on the software’s setup. Performance testing enables developers  to make sure these critical criteria are met.

  • Improving application’s performance 

This is obvious, but continuously fixing major and minor performance issues helps you establish aforementioned reliable foundation and make fewer mistakes later on. It’s a lengthy process — every time you launch a new feature, design, events, or make changes to the existing functionality, you need to test performance to ensure you’re not sacrificing for new additions.

  • Increasing user satisfaction

When you test your software, you ensure its quality and how responsive it is to users’ needs. Such testing is what, in turn, keeps your customers happy in the long run. Therefore, only rigid testing and strict quality assurance methods can guarantee your product’s success and meet your users’ hopes and demands. 

  • Reducing risks and eliminating bottlenecks 

Ideally, performance testing starts once the first lines of code appear. It lets you do away with all bugs and imperfections of your software before your users touch it. Moreover, testing your products acts as a tool for eradicating defects and as a process for modernizing and upgrading your product. 

The difference between load and performance testing, in a nutshell


Load testing and performance testing are the mainstays of optimized and seamless software performance. Load testing is centered around checking if the system can endure necessary load, while performance testing is concerned with evaluating whether or not the system’s main measurements are compliant with the required standards. These complex yet easy-to-conduct processes differ in some minor aspects, but are still similar in their purpose: they serve the uninterrupted performance of a product as well as excellent user experience. 


To sum up, let’s single out the main aspects in which load testing and performance testing differ.

Load testing:  

  • Smaller cost of failure
  • Detection of imperfect code and other bugs
  • Assurance of proper load endurance
  • Enhanced customer satisfaction 

Performance testing:

  • Assessment of the pivotal measurements of software’s quality: speed, stability, and scalability
  • Improved performance 
  • Broader evaluation of the system’s performance

Load testing and performance testing are two commonly used quality assurance practices that should be a broader part of your testing strategy. To get more help with QA strategy, you can check out our Insights blog or click on the link below to get in touch with one of our quality assurance strategists.



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