Writing efficient and clean ColdFusion code is not difficult. Attention to detail and an understanding of a few of the finer points of ColdFusion Markup Language are required. An understanding of how ColdFusion tags and functions work is all but mandatory. In addition, don't forget that one of the best pieces of advice that I can give you is to properly document your code with plenty of comments.
An often-overlooked method of improving application performance is examination of the database calls that your application is making to determine if you need to restructure logic to reduce trips to the database, to replace complex database queries with stored procedures, or to involve query caching for result sets that can be reused.
More often that not, the database is a critical bottleneck in the application, so it's best not to overlook that important piece when examining application performance.
For more on database tuning and caching, be sure to review Chapter 23, "Working with Databases," and Chapter 18, "Enhancing Application Performance with Caching."