I believe another key is to get testing as close to the development process as possible. For example, through multiple experiences we learned that when you develop a database app, the first thing to do is to build a database that is larger than expected and have the developers work against that database, not versions on their machines with only a few rows in each table. By doing this, in writing their code the developers have to live with any performance issues they might be introducing and will naturally address them out of self interest.