Question - Hibernate uses so much runtime reflection?
Answer -
Many former C or C++ programmers prefer generated-code solutions to runtime reflection. This is usually justified by reference to the performance red-herring. However, modern JVMs implement reflection extremely efficiently and the overhead is minimal compared to the cost of disk access or IPC. Developers from other traditions (eg. Smalltalk) have always relied upon reflection to do things that C/C++ needs code-generation for.
In the very latest versions of Hibernate, "reflection" is optimised via the CGLIB runtime bytecode generation library. This means that "reflected" property get / set calls no longer carry the overhead of the Java reflection API and are actually just normal method calls. This results in a (very) small performance gain.