JVM seems to include few new intesting optimization options
-XX:+UseCompressedStrings
-XX:+OptimizeStringConcat
-XX:+UseStringCache
Why these sounds interesting. Well, simply because strings are among the biggest memory consumers, and string manipulations like concat tends to be relatively slow.
Update:
OptimizeStringConcat is in JDK 1.6.0_18
References:
The Virtual Machinist: -XX:+UseCompressedStrings explained
Google Groups: Description of -XX:+OptimizeStringConcat ?
Stackoverflow: JVM -XX:+StringCache argument?
Oracle: Java HotSpot VM Options
Kari’s World: Converting String to UTF8?
Kari’s World: Compact String Dictionary
Kari’s World: String Magic