You have unit and integration tests to ensure your application operates as intended and you don’t have to test in production. What happens (or fails to happen) when a large number of users wants to take advantage of your application’s functionality all at once? That’s where application performance testing comes in. Here, I’ll provide you with a list of things to think about (and watch out for) when simulating traffic to your site in a test environment, and pointers on using LoadImpact’s open-source K6 tool to do the job.