The method javassist.util.proxy.RuntimeSupport.find2methods has a synch block, called indirectly by ProxyFactory.createClass(). It is a strong bottleneck for frameworks as Hibernate which can use it several times in a large set of data proxied.
Javassist 3.17.0-GA fixes it. Hibernate should update its current javassist version: https://issues.jboss.org/browse/JASSIST-163