DoctrineのメモリーリークについてThe document compares the performance of Doctrine 1 and Doctrine 2 in PHP 5.2.14, PHP 5.3.5, and EC2. It shows that Doctrine 2 has better performance than Doctrine 1 due to its use of clear() to remove objects from memory instead of relying on PHP's garbage collection. It also demonstrates that Doctrine 1 has improved performance in PHP 5.3 thanks to faster object destruction.
