Optimize reflection on entities

[mikey]

On each request to the persistence API reflection is done on the entity class. If you have a page which selects a single instance and wants to do an update on the instance, this will lead to two reflections on the entity class. This could be optimized in a way that only one reflection would be required. It could even be enhanced in a way that the reflection result is cached in production mode, as it is most likely that the entity class does not change between requests.

[mikey]

Realized with r1925. However, now caching inbetween requests was introduced. First we want to measure the improvements with the new behaviour.

[mikey]

Caching between request will not be introduced now.