[Joeri]

Except that nothing says that you need deep class hierarchies. In fact, i think heavy use of classes and class hierarchies is an anti-pattern in PHP because of its procedural per-request model.

Typically php frameworks follow a java-style model of unserializing data into objects, loading the corresponding class files on-demand, calling API's on the objects, and then reserializing. It is _much_ faster if you treat the data as a stream, cutting it up and transforming it as it passes through your code, without ever building up an object representation, and not doing any more deserialization than a simple json_decode (which is really fast). This is in fact the original PHP model, transforming a stream of annotated HTML.