Top 25 System Performance Testing Interview Questions and Answers in 2024

Editorial Team

Top 25 System Performance Testing Interview Questions

The following interview questions and answers will help you prepare adequately for your next interview.

1. Define The Term Performance Testing.

Performance testing is the process of testing the quality attributes of an application to see how it will perform when assigned tasks. Testing software is introduced into the application for the main purpose of figuring out if that particular application can still sustain its normal stability, scalability, and speed.

2. What Factors Should Be Considered When Selecting Performance Tools?

When selecting performance tools you should keep in mind factors like the availability of a testing environment to make your work easier, the cost of the license, tools that are preferred by most customers, how efficient the tool is, testing tool options for users, and protocol support.

3. State And Explain Different Types Of Performance Testing.

  • Stress testing. This is the processing of identifying the breaking point of an application by  putting it under extreme pressure by overloading it with tasks to see how the application handles high traffic
  • Load testing. This is measuring the performance capability of an application by assigning it with anticipated user tasks to see how it handles the task, this test is usually done before an application is released to the users.
  • Endurance testing. This is testing whether an application can be able to sustain its durability by handling the expected work load for a long time.
  • Scalability testing. This is measuring an applications capability to scale higher as the number of users also increase same as the work load
  • Volume testing. This is the overall testing of an is done after the system has been overpopulated so as to measure the applications overall software system capability.

4. Define The Term “Throughput” As It Is Used In Performance Testing.

Throughput is data that is generated to respond to requests by clients using a particular application, these requests are usually sent to the server. The value of throughput contributes a great deal to the performance of an application.

5. What Are Some Of The Common Mistakes Done When Conducting Performance Testing?

Some of the mistakes that programmers do when testing the performance of an application include:

  • Lacking sufficient populated data.
  • Not having long enough run durations.
  • Lack of valid test results.
  • Rushing for the mult user testing tools
  • Underestimating performance test results.
  • Underestimating the need of some performance tests.
  • Unsure about the required amount of work load.
  • Not knowing who the applications concurrent users are.

6. Explain The Difference Between Benchmark Testing And Baseline Testing.

Benchmarking testing is a method of testing where a programmer compares the performance of their software application against the expected standard of a particular company while Baseline testing is a method of testing where a programmer compares their current application software to the previous application software of an organization, in other words, it using a previous applications software as a reference for the next upgraded software

7. Why Is Performance Testing Essential?

Performance testing of an application is mainly important for a couple of reasons:

  • To figure out the duration an application to respond to the number of users intended for the application.
  • To figure out the resisting capacity of an application by overloading the system.
  • To figure out the highest number of users an application can handle when overloaded.
  • To correct any kind of limitation the application might have that might give the users some hard time in future.

8. Why Is Manual Load Testing No Longer Preferred By Programmers?

Manual load testing is no longer preferred by programmers due to its nature of complicated procedures. Manual load testing also has complex synchronization procedures that made it complicated for more users to use an application, and it is also difficult to assess the outcome of an application after the manual testing.

9. What Elements Should Be Considered When Conducting Performance Testing?

When conducting performance testing, elements that are being considered should be mostly related to why you are conducting the test and what you hope to get at the end of the testing. These elements include:

  • Detected errors
  • Throughputs from users.
  • Duration required to complete the performance test.
  • The number of users of a particular application.
  • Response time of the application.
  • Clients or user recommendations.
  • Changes of performance results reports compared to previous performance rate reports.
  • Why the application system has failed.
  • When the current performance of your application no longer matches your initial performance test results.
  • Availability of a spike caused by users that is affecting performance of the application’s software.

10. State All The Steps That Are Required For The Activity Of The Performance Test To Be Done?

  1. Gathering all the requirements related to the reason why the performance test is required.
  2. Selecting the best tool for the performance test.
  3. Coming up with a plan on how the performance test should be done.
  4. Developing the test that match the required modification of the application system.
  5. Modeling the taste to fit the exact level of threats that an application software may face.
  6. Executing the test on the application software.
  7. Observing and analyzing the results after the introduction of the threat to the software.
  8. Creating a report about what was observed and analyzed.
  9. Come up with a solution to any possible threats that might affect an applications performance negatively.

11. Discuss Some Of The Common Performance Problems Experienced By Application Software Users?

Some of the performance problems experienced by application users include long loading time when accessing the application, poor response from the same application, coding errors, poor scalability, and hardware-related issues.

12. Define And State The Two Types Of Performance Tuning.

Performance tuning can be described as the improvement of the performance of an application. The performance tuning of an application is only possible if a particular problem that mainly hinders its performance has been dealt with. Performance tuning is also possible if the problem that was anticipated to negatively affect the performance of an application has been prevented before the problem strikes. The two common types of performance tuning are:

  • Hardware tuning – this is improving a hardware system by adding or supplanting components.
  • Software tuning – this refers to improving the software of an application by the bottlenecks within the system and fixing them.

13. State The Different Components Of Loadrunner And Explain Their Benefits.

Different LoadRunner components include:

  • Load Generator – This component helps in the generation of the LoadRunner.
  • Controller – Controller is a component of the LoadRunner that creates, maintains and executes performance tests.
  • VuGen – This component keeps a record of real user actions on application.
  • Analysis – This component stores data reports that is related to the performance of an application system in form of graphs.

The benefits of LoadRunner performance testing tools are they provide robust reports, provide test cases results, have high versatility, and offer easy interrogation.

14. State The Difference Between Stress Testing And Soak Testing

Stress testing is a method of testing the performance of an application’s software by overloading it beyond the expected limit. The main reason for such a test is to see the capability of the application when it is under extreme pressure that is beyond the normal pressure. While soak testing is a method of testing the performance of application software for an extended period of time. The test is to figure out if the system can remain stable and still perform its tasks even after being used for a very long time. They both measure the strength of application software by adding pressures to see their stability.

15. Explain The Difference Between Performance Testing And Performance Engineering.

Performance testing is the processing of assessing an application software to figure out issues that might affect its performance and coming up with possible solutions to solve the problems. While performance engineering is the processing of solving the identified problems when conducting the performance testing.

16. What Software And Hardware Parameters Are Considered When Conducting A Performance Test?

Some of the parameters that are taken into consideration include the memory usage, the processor usage, the bandwidth, the memory page, the network output queue length, the response time, the CPU interruption per second, the committed memory, and the thread counts.

17. State The Differences Between Performance Testing And Functional Testing

  • Functional testing provides results on an application by measuring its input against the applications output, whereas performance testing measures the performance of an application at various loading stages during its performance.
  • Functional testing can be done either manually or it can be automated, while performance testing provides the best results when automated.
  • Functional testing require the involvement of customers and testers while performance testing require the involvement of Tester, Developer, DBA, and N/W management.
  • Functional testing does not necessarily require a testing environment however performance testing requires production test environment and H/W facilities to populate the load

18. Explain How You Can Identify And Rate Performance In Bottleneck Scenarios?

The best way to identify bottleneck scenarios so that you can rate the performance of an application in bottleneck situations is by monitoring the application against stress conditions. The user should use LoadRunner software to monitor the performance. LoadRunner will not only identify what affects the app negatively but will also identify conditions that can increase the performance level of application software.

19. What Does The Term NeoLoad Mean?

NeoLoad is a testing tool used in measuring the performance of application software. The tool is also capable of proving possible programmatic solutions to the developers of the application before the programmers release the applications into production.

20. State The Performance Test Steps In Jmeter

Creating a performance test plan in JMeter will require the developer to:

  • Add a thread group that will have the same goal of executing a similar task or a task in a similar scenario.
  • Add a JMeter element than help in performing several load test or several technologies.
  • Then add graphic results for easy understanding and identifying pattern trends on the performance of an application.
  • Run a test to figure out if the outcome of the results were either random or fixed.
  • Finally get the results.

21. Why Do Programmers Prefer Jmeter In Performance Testing?

There are several reasons why Jmeter has gained popularity among software developers. Jmeter has enabled developers to determine the maximum number of concurrent users an application can handle at a time; the software also provides several graphic analysis reports on performance testing. Applications developers also prefer Jmeter since it is software that can be used to test both statistics resources like JavaScript and dynamic resources like Ajax.

22. State And Explain The Automatic Phases In Performance Testing.

Automatic performance testing also has its own step-to-step procedure towards estimated results. The steps include:

  • Designing phase:  This is the process of building a test strategy that suits the application you want to test. While you are coming up with your strategy it will require you to include your thinking time, to also figure out the performance bottle neck of the intended application, you also need to learn from your previous experience with the same application, that is, if you are not testing it for the first time. It is during the designing phase that a developer should emphasize on Baseline testing too.
  • Building phase. This when the designing stage is already done and you have all that you require to completely make an extra ordinary change on the application to enhance its performance. It is where a developer works on the application making the necessary changes.
  • Execution phase. The execution stage is when the developer has finished making the necessary corrections or updates on an application, then they give it a test run to see how effective the changes were.
  • Analyzing and software tuning phase. The analyzing stage is when a developer observes their work to find out if there is still problems that they wanted to get rid of, and also if there is a new developed issue that may affect the user of the application. The programmer also uses this stage for software turning in case the application did not turn out as the developer expected.

23. How Would You Perform Spike Testing In Jmeter?

The best way is to use a synchronizing timer where the highest number of threads are continuously jammed into the system, then they are released at the same time. The release of these different threads at the same time will cause the application to experience an immediate extreme overload. This is where the programmer will observe the performance of the application under such a scenario.

24. Mention And Define At Least Five Common Performance Bottlenecks.

  • CPU utilization bottleneck.

There are two possible causes of CPU utilization bottleneck. The first one may be caused due to the CPU preprocessor running at over 80% capacity. The second possible cause is insufficient system memory.

  • Memory utilization bottleneck.

The most common reason that causes Memory utilization bottleneck is insufficient or fast enough RAM. Luck of enough memory causes the computer to start offloading storage via a very slow HDD or SSD to keep it running.

  • Software limitation bottleneck.

Software limitation bottleneck may be caused by programs that are only built to work with a single CPU. When they are linked to a stream of CPUs, they find it hard to handle a number of tasks at once.

  • Networking utilization bottleneck.

A networking utilization bottleneck occurs when two devices have a problem communicating with each other due to a lack of bandwidth. The lack of processing power between the two devices to enhance communication is due to the overloaded server and network between the two devices.

  • Disk usage bottleneck.

This type of bottleneck causes the reduction in the disk usage speed due to fragmentation issues

25. What Are The Best Things To Consider When Selecting A Performance Testing Tool?

Some of the things to consider when selecting a performance testing tool for your application include the ability of that performance tool to generate an adequate workload for your application’s software. You should also consider your capability of setting up a working environment for loading your application software. The performance testing tool should be able to analyze, detect and respond on time. The performance testing tool should be user-friendly to enable the user to have an easy time as they check the performance levels of their applications.

While you select your next performance tool, ensure it is compatible with your others performance testing tools. You shouldn’t choose software that might disrupt the normal working of other soft wares. The new performance software should be able to provide automated and first feedback. Figure out the cost of the performance testing tool. The cost of the tool should be within your budget limit. The performance testing tool should have the right set of protocols. It should be able to perform distributed testing and provide automated reports.


Study and practice these interview questions to ace your next interview. Be sure to arrive early and also dress decently for the interview.