In the LinkedIn-symfony-group I stumbled upon a very useful link:
http://labs.octivi.com/mastering-symfony2-performance-doctrine/
This is a must-read for all doctrine-beginners, I wish i woud have read it when I started… Here are the points in short:
- use the Symfony Profiler toolbar
- avoid object hydration
- use IDs for referencing rather than whole object
- use update-statement
- use lazy collections
- never load entities in a loop
More infos can be found in the article.