1. You do not optimize.
2. You do not optimize, without measuring first.
3. When the performance is not bound by the code, but by external factors, the optimization is over.
4. Only optimize code that already has full unit test coverage.
5. One factor at a time.
6. No unresolved bugs, no schedule pressure.
7. Testing will go on as long as it has to.
8. If this is your first night at Optimization Club, you have to write a test case.