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What makes a realistic load test

Performance testing covers a wide range of different tests. The benefits can vary whether you test a single URL or a complete user journey through the application. It might seem obvious, but to add the most value to your load tests you should make them as realistic as reasonably possible.

What is the point of making a test realistic?

Quick and unrealistic load tests often prove useless or even counterproductive. It is often the best way to be overwhelmed with unreliable data.


A realistic load test will allow you to:

  • Stress all layers of your application. This way you can assess the performance of all your servers and detect bottlenecks.
  • Pinpoint real bottlenecks. For example a simple load test based on a single URL might point to limitations on your front servers when actually the real users won't experience it because the backend is the first to fail.
  • Avoid false positives. If you fail to launch realistic tests and encounter a lot of errors, you might stress the CPU of your front servers to handle these errors. The same goes for the network if you don't simulate the load from the right location.

Preparations and prerequisites

During my past years as a tester, I often wondered how to get a higher customer satisfaction. I could go great lengths describing the required skill set and give examples (actually I already did that over here). When actually the truth is much simpler.

It's not rocket science, it's all about preparations and prerequisites.

Prepare to be prepared


Over the years, I have worked with a lot of testers. We more or less shared the same views on how to do our jobs and even when all was not going according to the plan.

Performance testing and objectives

There's no denying the importance of a performance test campaign in the quality assurance process. But I have lost count of customers requesting load test with no specific objective (or just "improve the performance"). Running a test campaign with no objective in mind is quite risky. You might spend a lot of efforts on useless improvements whereas the critical pain points remain.

Endless tuning


I worked on performance campaigns with no objective defined a couple of times. Usually, this implies running tests until you run out of time/budget and optimizing whatever you can. It does not mean these campaigns were not successful, but they probably cost a lot more money than they should have.

What makes a good performance tester

You have probably read countless articles about what a good tester is. Of course this is a tricky question and there is no perfect answer. Performance testing requires a mix of technical, organisational and communication skills.

I have seen good technical testers fail to deliver the right message even if they identified the source of all issues.

On the other hand, I have seen performance testers with low technical skills perform very well thanks to their communication.

There is no perfect mix of expertise I would recommend but instead, let's see what the testing challenges are.

What to do with my results

Since I started my career as a tester, I'm often impressed by how disregarded communication in load and performance testing is. However, you can be as skilled as you want as a technical tester, if you can't explain your analysis and convince decision makers to take actions, most of your work was in vain. In fact, I've seen colleagues who were not interested in the technical aspects of the job get better customer satisfaction. The good thing is, communication is just a skill amongst others that you can train.

Today I would like to share everything I learned about presenting results.

Once upon a time in my load test campaign

Once upon a time

In my opinion, you should always come up with a short story describing your load test campaign. Rest assured, it does not have to include fairies and princesses, the truth will do just fine. It allows everyone to understand quickly what happened during the campaign. And it's pretty obvious that a good story always sells better.