Lets talk Java theory

Garbage Collector (Algorithm used)
http://www.ibm.com/developerworks/java/library/j-jtp10283/
http://java.sun.com/docs/hotspot/gc1.4.2/faq.html
http://www.petefreitag.com/articles/gctuning/

Synchronization (Mutex, Semaphore & Monitor):
http://en.wikipedia.org/wiki/Mutual_exclusion
http://en.wikipedia.org/wiki/Semaphores
http://en.wikipedia.org/wiki/Monitor_(synchronization)

Java Code tuning:
Tuning Java Code
http://www.oreillynet.com/pub/a/oreilly/java/news/jptsummary_1100.html
http://www.javaperformancetuning.com/

Networking:
Three stage handshaking
http://en.kioskea.net/contents/internet/tcp.php3