Trove4J

I have just discovered a java library called Trove, which allows you to plug in their versions (eg THashMap) of certain containers (java.util.HashMap, java.util.HashSet, java.util.LinkedList), and use them just like you would with the standard versions gaining performance. For example the THashMap class is a faster than java.util.HashMap. Trove also comes when you download Repast.