Determine the functional and nonfunctional requirements of the project or application. Performance requirements are better when they are specific so that they are not misinterpreted and can actually be followed. Your performance requirements could look like the following examples. Note that no mention of the infrastructure is needed in this phase. The requirements here will also reflect any project SLAs that have been agreed.

• A user request to create a new account should complete in < 200ms
• Under a system load of 250 users retrieving credit card statements, 100% of requests should complete in < 5s, with 95% completing in < 500ms

Take aways

• Add performance requirements at the start of your project. There’s no such thing as no performance requirement.
• You performance requirements should be measurable, and precise.
• Avoid language such as “all” and “every”. Try to be explicit with your requirements.

Next Stage: Design