Performance Testing Interview Questions with Answers Guide

A complete understanding of software performance is impossible without the help of qualified performance testers. According to a MarketsandMarkets report, the crowdsourced testing market is projected to grow from USD 12.6 Billion in 2019 to USD 28.8 billion by 2024. This means equally attractive opportunities for employees and employers. Hence, the database of potential performance testing candidates will continue to multiply. 

For companies looking to clinch the best candidates from the talent foundry, meticulous and detailed recruitment is key. At the same time, without a knowledge of relevant performance testing interview questions and answers, finding an apt candidate to conduct a performance test will, in fact, become grueling. To make things easier for you, we came up with this invaluable compendium of questions that we deem fit to ask the candidates offering performance testing services to your organization.

This set of questions are culled from years of experience in solving intricate problems in penetration QA processes. They will help you make the most out of your recruitment and should be adequately answered by the most suitable candidates. Also, do check out our blog post on Top 50 Software Testing Interview Questions and Answers if you’re interested in working with a diverse team of QA engineers.  

1. Explain Performance Testing 

Performance testing, just as its name implies, is a process of conducting professional checks on all the operations of software. In order words, performance testing analyzes how well the functions of a software carry out their duties. 

It is essential to understand that performance testing does not just check whether the software’s functionalities are operational. Ideally, performance testing checks how well, how fast, how slow, how effectively the functionalities operate. For instance, after a performance test is carried out, it can be discovered that a particular addition function in a calculator is working at a prolonged rate when initiated. 

2. Outline the Types of Performance Testing 

Various types of performance tests can be carried out on software. However, it is vital to know that most performance tests are broad and can inculcate multiple performance tests into a single test program. 

We have outlined some of the most common types of performance tests, including:

• Load testing 
• Endurance testing 
• Stress testing 
• Spike testing 
• Volume testing 
• Scalability testing.

3. Explain Load Testing 

Load testing is the process of analyzing the performance of software as it is receiving data. This test is used to know how well the software will operate when it is saddled with many loads. The load can be data or information of any kind. Within an operating system, the load can be an application or a program. Some software can start performing slowly when much data is processed through it, while some continue to operate at an optimal level no matter how much information is being processed.  

4. Explain Endurance Testing 

Endurance testing is quite similar to load testing; however, endurance testing has more to do with how long rather than how much. Endurance testing analyses how long and how well software can perform its functions regardless of its load. Some software becomes slow or inactive when used for a long time while others do not crack with time. Endurance testing simulates the lengthy usage of software and analyses all the changes within its performance levels.  

5. Explain Stress Testing 

Stress testing takes a broader approach when dealing with the performance of the software. It takes into consideration the amount of data being processed, together with the length of time taken to process the data, together with the connectivity levels, and the other software running in the background of the operating system. 

Some software tends to give in when the stress levels are high, and stress testing imitates the effects that a stressful situation will pose to the software. Conducting a stress test will help you improve your software’s resistance to be able to operate correctly, even with imposed high-stress levels. 

6. Explain Spike Testing 

This type of testing is equivalent to pushing the software to the edge of its performance. Spike testing induces the software’s highest possible operation level to analyze its potential and weaknesses that require improvements. For instance, when vehicle manufacturers are testing the engine of a car being assembled, they conduct a spike test on the engine by running it independently to the extent that the engine body becomes red hot. Usually, a customer will not use the car to the extent that the engine turns red hot. However, that spike test is conducted to be doubly sure that the engine will not break down easily. Almost the same principle is applied while spiking testing software. It is simply pushed to its limits. 

7. Explain Scalability Testing 

Scalability testing is analyzing how well software transitions from a simple operation capacity to a complex operation capacity. Some software take time before getting used to a complex operation after spending so much time doing simple operations. The ability to scale quickly without any drawback is determined by carrying out a scalability test. 

8. Explain the Most Common Performance Issues 

The software might be too slow to respond. The software might have a repetitive loop. The software may be shutting down whenever it gets to a certain point of operation or hanging uncontrollably. It might have an insufficient amount of storage. The software might also simply not be compatible with a particular operating system or device version. 

These issues are generally due to various factors, including an increase in the amount of data being processed, how long the software had been running, the available connectivity level, the network established between the software and an external source, etc.  

9. Explain a Performance Testing Procedure

Firstly, the software to be tested should be analyzed, and its performance levels before the test should be documented. 

Secondly, the testing medium that will be used to carry out the test should be analyzed. Whether it’s going to be an automated performance test or a manual one, the automated system and the manual testers have to be cross-checked. 

Next, the performance test should be executed accordingly. All outcomes should be monitored as the test progresses, and after the test, all the results must be adequately documented.  

10. Differentiate between Functional Testing and Performance Testing 

Functional testing involves checking whether the different software functionalities are doing what they were initially programmed to do. For instance, can a calculator software perform essential functions like addition, subtraction, etc.? 

In the case of Performance testing, the correct functionalities are analyzed to determine how well they perform. For instance, those essential calculator functions we stated earlier might be operating at a very slow rate. The calculator’s core might not synchronize well with the basic functions, causing a glitch.  

11. How does Endurance Testing Differ from Spike Testing?

These two tests are similar but have their differences. 

Endurance testing has to do with time. It checks how long a software can operate at an optimal level, while spike testing has to do with a quick sharp rise in the software’s operational status. It checks software by pressing towards its highest possible operating level. One can say that spike testing has to do with reaching the highest operating limits, while endurance testing has to do with how long it will take for the software to be affected by its operations. 

Endurance testing doesn’t have to depend on the amount of data being processed by the software. It depends on time. While spike testing can depend on the amount of data being processed, it does not rely on the time taken. 

12. What Is the Best Way to Carry out Spike Testing? 

The best way to carry out spike testing is to bombard the software with data, operations, random connections, networking, filling up the software storage, and initiating every single functionality. This way, the software is pushed to its limit and may or may not crack under such pressure. The critical thing to do is to document its performance changes as it is being bombarded with operations. 

13. Explain Common Pitfalls to Avoid During Performance Testing 

While carrying out a performance test, do not be quick to allow multiple test systems or testers all at once. Each test has to be executed by one particular tester at a time to gather a more accurate conclusion. Running one test with multiple testers can muddle up the process. 

Before, during, and after each performance test, you must document the software’s amount of workload. Without documenting the workloads, you will not know the breaking points, or weaknesses, or strengths of the software.

 Most times, neglecting the testing of some functionalities of the software can be costly in the future. Do not ignore any function, no matter how small it may seem. A little function that malfunctions can freeze the whole software. 

14. Explain the Term “Throughput”

This refers to the number of operations carried out by software in relation to the time frame within which such operations are performed. For instance, for a call software, the amount of incoming and outgoing calls per second, per minute, per day, per week, per month, or per year, all represent the software’s throughput. Thus, one can firmly state that the throughput of software is equal to the operation amount divided by the time taken during the operation. 

15. How Does Benchmark Testing Differ from Baseline Testing?

Benchmark testing has to do with testing software based on the certified market standards that regulate the sector. In other words, the software is tested, and its performance is compared to the standards set by the regulatory bodies and standards organizations. This is to ensure that the software meets and exceeds the certified regulatory standards. 

Baseline testing involves testing software and comparing its performance to previously documented performance levels. In other words, a test is carried out first, and when a second test is carried out, the most recent test is compared to the results from the previous test to ascertain the level of progress achieved. 

16. Explain the Term “Performance Tuning”

As its name implies, this is the process of improving software performance levels after you must have conducted a test to identify where an upgrade is needed. During performance tuning, codes are re-written, storage capacities are enlarged, networking capabilities are readjusted, compatibility is improved, endurance levels are improved, immunity is introduced to some areas, etc. Performance tuning is simply correcting the software’s drawbacks and raising its standard to accommodate higher operational levels.

17. Explain “Caching” During Performance Testing 

During performance testing, information is automatically cached or stored temporarily. It is highly not recommended for testers to rely on cached data because of its unstable and temporary nature. However, cached data can provide in-depth minor details that can easily be overlooked, such as the adverts on a particular web page. 

18. Outline the Major Tools for Performance Testing 

It is imperative to understand that out of the many tools for carrying out performance tests, only a few have been highly secure, accurate, and useful. An experienced performance tester should be able to identify the best tools. He/ she should be highly knowledgeable in using the best tools. He/ she should also have a black book of dangerous tools that should never be used. 

Here are some of the best tools for performance testing: 

• LoadView
• Apache JMeter
• LoadUI Pro
• WebLoad
• NeoLoad

19. Explain the Term “Protocol”

As its name implies, a protocol is simply the guidelines that oversee, authorize, or restrict the transfer to data or the interaction between two or multiple systems. Protocols are set up to create orderly communication networks that meet the specifications of each other. There are simple protocols, and there are complex ones, depending on the communication network being established and on the various systems doing the interaction themselves. Here are some standard protocols: 

• HTTP: Hypertext Transfer Protocol. 
• HTTPS: Hypertext Transfer Protocol Secure. 
• FTP: File Transfer Protocol. 
• SMTP: Simple Mail Transfer Protocol. 
• Citrix Independent Computing Architecture.

20. Explain the Different Types of Performance tuning 

There are two types of performance tuning, namely: Hardware tuning and Software tuning. 

Hardware tuning is the process of improving the physical structure of a system, which can include its physical design, its skeletal construction, its ports, its antennas, its lighting systems, etc. 

Software tuning is the process of improving the performance levels of digital software. As explained earlier, software tuning has to do with re-writing codes, enlarging storage capabilities, readjusting networking capabilities, improving internal compatibility, improving endurance levels, introducing immunity to some areas, etc. 

We all understand the difference between hardware and software, so the above tuning comparison should be easy to grasp.  

21. What Are the Advantages of Performance Testing? 

• Performance testing helps an organization improve upon its software by determining its functionalities’ operation level. 
• Performance testing prevents an organization from launching a half-baked software, leading to a loss of reputation and customers. 
• Performance testing helps an organization to discover and layout the most favorable system specifications for its software. This will help the end-users to know what type of system is most compatible with the software. 
• A newly developed software that hasn’t been launched to the public should be tested to ascertain its strengths and weaknesses. The weaknesses can then be improved upon before it is launched.  

22. Explain the Term “Profiling” During Performance Testing 

Profiling is an identification process that picks out the issues impeding the optimal operation of a software’s functionalities. During performance testing, profiling helps identify the smallest performance defects that may not be fully expatriated during the test. All the details of such issues are brought to light, including their location, programming structure, type, size, etc. 

23. Explain the Term “Soak Testing” 

Soak testing is a type of performance testing where a particular load or circumstance is continually fed or introduced to the software over a long period to ascertain how well software will operate with an absolute load. Simply put, the software is soaked with a particular load or function. This way, the organization becomes fully aware of how their software will react to that specific load. 

24. Explain How Performance Testing Differs from Performance Engineering 

Performance testing is the process of analyzing and finding out the performance levels of a software’s functionalities. In contrast, performance engineering is the process of correcting all the issues discovered during a performance test. Simply put, the performance test finds the performance inadequacies while performance engineering deals with upgrading the software to its best performance levels. 

25. Describe the Term “Bottlenecks” in a Software 

Bottlenecks are the performance issues faced by software. As explained earlier, the commonly encountered bottlenecks are: 

• When software might be too slow to respond. 
• The software might have a repetitive loop. 
• The software may be shutting down whenever it gets to a certain point of operation. 
• The software might be hanging uncontrollably.
• The software might have an insufficient amount of storage. 
• The software might not be compatible with a particular operating system or device version

All these issues can be referred to as Bottlenecks. 

26. Can End-users Carry out Performance Testing? 

To an extent, end-users unknowingly carry out performance tests as they make use of the software. Although this cannot be equated to a practical professional performance test, end-users can also discover bottlenecks in software. 

To answer the question: No, end-users cannot carry out performance testing; however, they can discover bottlenecks while using the software. If at all, users must participate in the testing process, then it’s best at the User-Acceptance Testing Phase.  

27. Explain the Term “Concurrent User Hits”

This term can be described as the number of times in a moment that particular functionality is initiated in software. For instance, in a web app, the concurrent user hits on the ‘Homepage’ can be twice as much as that of the ‘Contact Us.’ 

Some software can develop bottlenecks when there’s a high amount of concurrent user hits, which can be detected during performance testing.  

28. Describe Your Overall Performance Testing Experience 

Here, the candidate will talk about their experiences with performance testing. They should be able to answer questions like: 

• How many performance tests they have carried out. 
• The most common and least common Bottlenecks they have encountered. 
• Their most used performance testing tools. 
• Whether they have any performance testing professional certification. 
• The types of software they have tested over time.
• Any questions that will tell you more about their level of experience should be asked. 

29. Explain Your Most Difficult Performance Testing Experience 

The candidate should be able to explain their most difficult performance testing experience adequately. Using this skill set will help you to understand their weaknesses and how they were able to improve. Difficulties are meant to serve as stepping stones to a higher and more professional level. Experience, they say, is the best teacher, and when the going gets tough, the tough get going.  

30. Why Should We Hire You? 

This question must be answered by the candidate with a high level of enthusiasm and confidence. They should be able to demonstrate that they did some research about your company and should be able to state the value they will add to the company. The idea is for the candidate to make a compelling and professional statement concerning carrying out a performance test on your software.  

What’s Next?

Great candidates don’t just want to know what you think: they want to know what your business plans and future needs are, and how they can contribute to those plans. As you already know, every player faces a significant challenge—could be technology adoption, ever-changing market trends, mega competition, and shifting of budgets for more profits. 

According to MarketsandMarkets.com, the crowdsourced performance testing market size is projected to grow from 1.3 billion dollars in 2019 to 2 billion dollars in 2024. To keep ahead of the pack and leverage most of these market size advantages, you need to place your business with the best talents. Testers at Utor combine both Agile Methodologies and customer-specific approaches in providing software testing solutions to clients. 

Hopefully, this guide will streamline the task of hiring a performance QA team. We’d love to hear your opinions and feedback on other useful performance testing questions and answers.