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What Is Load Testing in Software and Why You Need It?

Mar 6, 2020
8 min read

Load testing is a type of software testing that enables teams to evaluate software performance under varying user loads. The main purpose of load testing is to test the application under expected real-world scenarios.

Testing professionals usually apply load testing when the project is nearing its completion. With that said, load testing is not limited to a software system or application. It is a performance metric and can be applied to computers, servers, networks, and other peripheral devices, as well.

Load testing is necessary because the quality of any software system hinges on how well you identify underlying vulnerabilities. Unless you perform load testing, there’s no way of knowing how an application will behave in a real-world environment.

Furthermore, the risk of the application crashing will be significantly higher in the absence of load testing. In this article, we will discuss the importance of load testing in software development.

Why Is Software Load Testing So Important?

The usage of the internet in society has grown considerably in the past couple of decades. According to Statista, the world’s current population of active internet users is 4.47 billion. With the increasing number of internet users, websites, as well as web applications, need to extremely robust in terms of balancing user loads. 

why is performance testing so important

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At the same time, application users are now demanding greater user experience than before. Due to the tough competition in the software market, countless applications, web apps, and websites are now available for users to choose from.

As a result, users now have high expectations of software, and they prefer solutions that give them the best user experience. According to one source, 1-second delays in response time cause a 16% decline in user satisfaction.

Load testing is an essential non-functional requirement for software. It helps us identify whether our hardware, network, and software resources are sufficient for handling the expected user load. Software testing teams utilize load tests for testing input/output reads, network throughputs and the utilization of memory and server resources.

At the same time, load testing helps testers detect and resolve bottlenecks within software before they reach the production environment. To put it simply, load testing for web applications is essential for creating the ideal user experience (UX) and increasing the quality of the final product.

Benefits of Software Load Testing

Load testing in software testing has several benefits. Here are some of the main benefits of QA load testing:

Improved Loading Time

To enhance the user experience, your application needs to minimize loading times. A slow software or website not only makes users impatient but also causes them to leave the website. If you depend on your application or website for driving revenue, then load testing can help improve loading times for both web applications and software.

Minimizes the Risk for System Downtime

Studies show that 59% of Fortune 500 companies suffer from losses worth $46 million each year, even if they only have 96 minutes of downtime in a week. Load testing, along with stress testing, enables testers to simulate real-time app usage under varying loads.

When the system is subjected to increased traffic, it can outline issues that cause downtimes. Therefore, it is easier to resolve problems before they cause downtimes, and the overall likelihood of the system downtime is lower.

Improved Scalability

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.

Greater Customers Satisfaction

When a software team evaluates the key issues resulting from increased user loads, they can identify problems related to delayed response time and software quality. Since software teams detect these issues before the release of the application, they are able to resolve those issues before production.

In most cases, load testing helps companies eliminate issues such as delayed response times and enhances the quality of the product overall. Therefore, customers can enjoy a greater level of user satisfaction due to load testing.

Minimizes the Cost of Failure

The cost of identifying performance issues at an early stage is significantly less when compared to later stages. If your web application starts to show its bugs after the launch, it can irreparably damage your company’s reputation.

Until you fix all the bugs, you will either have to recall the application and move back to a previous version or halt your web app. Therefore, the resulting costs are always going to be taxing for your company and damage it severely. Gartner reports that downtime can cost companies as much as $300,000 per hour, on average.

Load testing enables you to detect these problems before your web app goes into a production environment. As a result, it is considerably easier to resolve these issues, and you don’t need to pay the costs of post-launch error removal.

Identify Inefficient Code

If your product has a complexly written code, then it will not utilize resources efficiently. However, these problems are hard to detect in normal circumstances, and we need load testing to identify these issues.

Establishing Service Level Agreements (SLAs)

A service-level agreement (SLA) is a mutually agreed contract between a client and a service provider. Both parties agree upon key aspects of a service or product, such as availability, quality, and responsibilities for a service or product.

Load testing enables software teams to test the capacity of a particular application. As a result, it is easier for the software team to conduct capacity planning. Capacity planning is necessary to determine which software and hardware resources are required to run an application.

Load testing plays a key role in determining how applications perform under heavy user loads. Therefore, it’s easier for software teams to come with service level agreements for their products.

The Goal of Load Testing in Software Testing

The goal of load testing is to expose the vulnerabilities of a system. However, load testing specializes in only identifying defects directly related to user loads.. Software testers use load testing to identify memory leaks, buffer overflow, and memory mismanagement within an application.

Another purpose of load testing is software development is to expose major issues in a system. These issues can range from load balancing problems and the capacity limitation of a system to bandwidth issues in a network.

Similarly, load testing helps testers to find out the upper limit of all major components of applications such as database, network applications, hardware, etc. Therefore, we can determine the anticipated load on an application in the future.

Use Cases and Examples of Load Testing in Software Development

Testers carry out load testing for accurately measuring the performance of a single system or comparing different systems under similar conditions. Similarly, some testers apply load testing in running environments to obtain real-time qualitative data about the system’s performance. Here are some of the most common examples of load testing in software development.

Measuring SQL Server Performance

The majority of websites work together with database servers. For instance, e-commerce websites utilize web pages for user interface but use database tables to store information related to customers and goods.

Load testing can help us identify if the database server is experiencing bottlenecks or not. We can use evaluate the performance of database servers based on the effectiveness of caching and memory management and the number of transactions performed.

Setting Reasonable Goals for SLAs

As mentioned above, SLAs are contracts between you and the client. Software teams are bound to the terms they agree within SLAs. Load testing helps teams understand the limitations of their application, website or product.

For web developers, load testing is necessary for monitoring time to first byte, website page load time, and other performance metrics. By performing a software load test, it’s easier to define SLA thresholds accurately for the website.

Retail Websites during Black Friday and Other Promotional Events

On occasions such as Black Friday, retail websites receive an insurmountable amount of user traffic. In the UK alone, the Amazon website received 49.98 million visits on Black Friday. Without load testing, it’s impossible to optimize a website for serving this many users simultaneously.

retail websites during black friday and other promotional events

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Testing If a Server Supports a Particular User Load

One of the most common use cases of load testing in software development is to verify whether a server is capable of supporting a given number of users concurrently. To carry out load tests for this purpose, we can generate virtual users that play on recorded scenarios. With the help of virtual user simulation and load testing, we can measure the user capacity of a server.

Measuring Resource Performance

Performance monitoring is an integral application of load testing. Aside from monitoring software behavior under varying load, load testing is essential for keeping an eye on resource usage.

If there are bottlenecks in memory management, disk IO, or network, the performance of the application is automatically affected. Software teams use several performance metrics such as processor, memory, network, and disk to detect bottlenecks in hardware performance.

Testing Government Portals

At a particular time of the year, some governments overrun their websites with a vast number of users. One common example of this is government websites catering to tax filers. Websites such as IRS receive a spike in user traffic, particularly during the filing date of income tax returns.

Who Needs Load Testing in Software

Regardless of which industry you belong to, load testing is essential for ensuring the performance of both hardware and software. It helps software teams identify Key Performance Indicators (KPIs) such as error rate, response time, CPU performance and memory leakage.

All these KPIs usually function 100% during functional testing. However, when we scale over to hundreds or thousands of users and simulate web traffic from different corners of the world, these KPIs worsen significantly.

Load testing helps businesses understand when and where their systems can break. Detecting these problems and fixing them can enable businesses to prevent revenue loss caused by downtimes and unsatisfied customers.

Furthermore, there is more than one type of load testing. For instance, we perform spike testing to see how the application reacts to different user loads. In such scenarios, we simulate a heavy user load gradually by beginning with the expected user load and increasing it over time.

Such applications of load testing are useful regardless of whether you are responsible for the development of a multinational website or a developer working on your own small scale system.

Even if you have conducted load tests earlier, your software can still behave unexpectedly, if you make modifications to the code. Due to the dependencies in codes, heisenbugs, and other issues, even small changes can cause the entire application to misbehave; hence, load testing is necessary at all stages of software development.

Do You Want to Load Test Your Product?
Drop us a line to find out what our team can do for you.


To summarize, load testing allows us to identify is critical issues within applications caused by user loads. Therefore, load testing is vital for maintaining the quality of software and ensuring that it performs well under all circumstances.

However, if you want to identify all performance bottlenecks accurately, you need to trust a reliable software testing service. PFLB is a software testing service that has experience of serving over 500 companies across all domains, from finance and healthcare to retail and technology.

With years of experience at their disposal, they can ensure that your mobile application delivers the highest quality and outperforms competing applications.

Besides Performance Testing, the company has expertise in other core software testing services, such as Manual Testing, Usability Testing, Integration Testing, Test Automation, and much more. To learn more about the company, feel free to visit their website at PFLB.

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