Is it better to assess performance during development process or at the end? – Difference between Agile and Waterfall approaches

Teams must identify at what point in the development process they will benefit the most from doing performance tests while considering the performance of existing systems or those constructed from the ground up. So, the goal of this post is to answer the question of whether we should start performance testing early on, alongside development (as in the agile approach) or later on (as in the waterfall style). Basically, difference between agile and waterfall approaches on performing performance tests at optimum time, will be discussed.

The agile approach involves starting performance testing early in the development process and continuing it throughout the application’s lifecycle.

The waterfall approach involves deferring all performance testing activities until the end of development, as acceptance testing, to ensure that the system performs as expected.

Let’s see what they contain, as well as the benefits and disadvantages of them.

Waterfall Approach

We normally wait till the conclusion of development to begin testing in this technique. Acceptance testing is used for the performance tests, and if the requirements are met, the system is ready for production. Simulating the projected load scenario is part of this process.


  • Normally, you strive to create a test environment that is as close to production as possible, which is advantageous because it is more realistic.
  • Because performance testing is only done for a certain amount of time, it is easy to organize and assign resources.
  • It enables the testing of certain properties (like Z number of functionalities under a specific context).


  • Waiting until the very end to ensure performance carries a significant risk because you cannot know how much work you’ll have ahead of you to go back and fix things to meet your performance goals.
  • While it’s excellent that we’re testing in a comparable environment to that of production, obtaining the infrastructure for exclusive use for the tests (you must isolate the SUT to get reliable results) can be tough.
  • Making architectural changes near the end of development (assuming testing reveals that they are required) is expensive.

Agile Approach

When it comes to performance testing, the agile method recommends starting with unit tests. It is critical to have a continuous integration system in place, as this allows us to undertake performance engineering rather than just performance testing.


  • Make continuous integration easier.
  • As you progress, learn about best practices, and strive to improve. If you start testing early, you’ll have more time to catch your mistakes and avoid them in the future. It’s excellent for preventing the spread of bad practices throughout the system.
  • Reduce the risk as much as possible.
  • Get early and consistent feedback.


  • Writing and maintaining scripts involves greater automation work.
  • If you automate too little or too much at particular levels, problems may develop. It’s best, for example, to automate as many unit performance tests as possible, with some at the API level and only the most critical test cases at the GUI level. This is similar to Michael Cohn’s automation pyramid concept; however it is focused on performance. You should be aware that you will need to consider what a performance unit test is in your specific situation.
  • Teams may fail to understand that it is a misconception to believe that if you test each component separately, the system would work well. That isn’t always the case. To acquire the greatest results, you must first test the components individually and then test them operating together.

I want to find the right testing type for my product

I want QA experts to test my application

I’m looking for a long-term testing partner   

I want to consult a QA Specialist   

When deciding between these two techniques, it’s crucial to consider the people, technology, and processes you’ll be working with. For performance testing, it is critical to have testers with both soft and hard skills. You must also consider which tools to use for load testing (e.g., JMeter, Gatling, etc.) and monitoring on both the server and client sides (e.g., New Relic). Test design, test automation, test execution, and measurement are all processes. We propose testing against a baseline and then using an iterative, incremental approach when creating an execution plan.

So, which method is best for you? It all depends on what you want to achieve.

When Should You Use The Waterfall Approach?

At the end, you might want to perform a load simulation when:

  • If you believe that specific tailoring is required for the context in which the program will execute.
  • You must ensure that your current system can handle a specific load.
  • Your consumers demand proof that your system performs up to a specific level (for example, if your client has an e-commerce website and wants to make sure that its online system can support 100,000 daily users).

When Should You Use The Agile Approach?

This approach, which includes performance engineering throughout development, may be required when:

  • If you wish to lower your risk and expenses.
  • Because they learn about performance engineering and monitoring throughout the process, you want to expand the team’s aggregate understanding of the subject.
  • When you want to stick to a continuous integration plan.


Can we say with certainty that one approach is superior to the other in every situation?

Of course, not.

Both approaches are required at various stages of development cycle. We should begin by performing performance engineering and simulating load for acceptability testing.

Actually, the two approaches aren’t that dissimilar. Both require the same people, technology, and processes, but they differ slightly depending on where you are in the development process.

That’s why; it is significant to decide on either one, in accordance with your current project and needs. For having more details and consultancy, you can request a demo from Loadium, here. We are always ready to respond your questions.

Happy Load Testing!