Rule #48
Do you avoid reviewing performance without metrics?
  v9.0 Posted at 4/09/2014 6:04 AM by tiagoaraujo

If a client says:

"This application is too slow, I don't really want to put up with such poor performance. Please fix."

We don't jump in and look at the code and clean it up and reply with something like:

"I've looked at the code and cleaned it up - not sure if this is suitable - please tell me if you are OK with the performance now."

A better way is:

  • Ask the client to tell us how slow it is (in seconds) and how fast they ideally would like it (in seconds)
  • Add some code to record the time the function takes to run
  • Reproduce the steps and record the time
  • Change the code
  • Reproduce the steps and record the time again
  • Reply to the customer:
    "It was 22 seconds, you asked for around 10 seconds. It is now 8 seconds."
 Figure: Good example – Add some code to check the timing, before fixing any performance issues (An example from SSW Code Auditor)

This is because performance is an emotional thing, sometimes it just *feels* slower. Without numbers, a person cannot really know for sure whether something has become quicker.

Related

For sample code on how to measure performance for windows application form, please refer to rule Do you have tests for Performance? on Rules To Better Unit Tests.

Related Rule​