I was reading over: http://java.sun.com/javase/6/webnotes/6u14.html, and I was wondering if anyone had tried various combinations of the new command line tweaks while running drools benchmarks. -XX:+DoEscapeAnalysis When hotspot is compiling a method, if it sees an object that is only used by a single thread within the method scope, it can avoid allocating it on the heap ! could be good for lots of small objects. Takes a load off the GC. My intuition is that this is an automatic version of defining a "struct" in C# (which only ever lives on the stack) but I might be mis-reading it... (probably am). -XX:+UseCompressedOops If using 64 bit JVM, and heap is < 32gig, this is supposed to help - can avoid pointers needing to be the platforms native 64bits when its clearly overkill... -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC This might not be experimental in a more recent version: but turns on the G1 GC, which is a new design, could eliminate a lot of pauses... I would love to hear if people play with these settings what the changes are with some of the benchmarks ! -- Michael D Neale home: www.michaelneale.net blog: michaelneale.blogspot.com