Cache is the performance killer for Web Application

An article, that describe potential web application performance improvement: http://highscalability.com/blog/2013/1/30/better-browser-caching-is-more-important-than-no-javascript.html

JDK 8 Milestones

http://openjdk.java.net/projects/jdk8/milestones

Java collections for primitive types

Java collections that save memory, when elements are primitive types:
http://trove.starlight-systems.com/overview

Ease of creating immutable collection woth Guava

In case of need od creating immutable collections in java, that are nice created, safe and efficient look for guava implementations
Read examples here: http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained