A couple other things: -XX:+UseCompressedOops converts many 64-bit references into 32-bit, trading a bit of CPU for a lot of memory If you use a lot of thread

A couple other things: -XX:+UseCompressedOops converts many 64-bit references into 32-bit, trading a bit of CPU for a lot of memory If you use a lot of threads, lower your stack size (-Xss) (no real method here, just drive some trucks over the bridge until it breaks, and that's your weight limit :P ) You don't want to swap! A good rule of thumb is to make your max heap (-Xmx) about 60% of total RAM if you only have 1 JVM running Adaptive GC tuning algorithms can become unstable in long-running processes. I like to use -XX:GCTimeRatio for the throughput collector which effectively turns off the adaptive stuff. CMSInitiatingOccupancyFraction/UseCMSInitiatingOccupancyOnlydoes the same thing for the concurrent mark-sweep colletor. Keep the ice pick handy :P