Then assign the JVM less RAM and suffer worse performance -- it's often a simple tradeoff you can make when launching the app. It would still likely be faster than most other choices (certainly all other GCed environments).
Did that (reduce heap size), ended up having 30 minute GC loops. Implementation in another <unnamed, new> language decreased memory usage rather radically.
Well, I guess I could have also done Structure of Arrays implementation and additionally avoided 'new', but it's not Java anymore at that point, is it? Easier to just write it in another language at that point.
Generic branchy business logic type code is indeed about as fast in C++ as in Java. But that doesn't hold for all types of software.
How fast is Java native floating point math vs. C++/intrinsics? Last I checked, C++/intrinsics seemed to have 2-8x lead. What about sorting? Last I checked C++/intrinsics sort seemed to be about 20-50x faster versus Java.
