Comparing the Java Serialization Options - http://www.theserverside.com/news/thread.tss?track=NL-461&ad=725624&thread_id=57871&asrc=EM_NLN_9286283&uid=703565 

Use Unsafe for best performance Serialization - http://mechanical-sympathy.blogspot.com.au/2012/07/native-cc-like-performance-for-java.html

off heap serialization - http://java-is-the-new-c.blogspot.com.au/2014/12/a-persistent-keyvalue-server-in-40.html