The much talked about and often cursed part of Java development is Garbage Collection.
I often say, “Writing code in Java is easy, but writing good code is extremely hard”
I have listed a list of links at the end of this article that provides more detailed information.
Resources:
http://java.sun.com/docs/hotspot/gc1.4.2/index.html
http://java.sun.com/docs/hotspot/PerformanceFAQ.html#1