1. Design the program well
2. Implement the program well**
3. Test the program well
4. Only after you're sure it's working, measure performance
5. If (and only if) performance is inadequate, find the "hot spots"
6. Tune the code to fix these
7. Repeat measure-analyse-tune cycle until performance ok

(** see "Programming Pearls", "Practice of Programming", etc. etc.)