>Yeah, you allocate a large pool of objects up front and manually reference count them. Every high-performance Java application I've seen ends up doing this

Not sure if it's still relevant, though.

One popular physics library years ago went as far as instrumenting compiled bytecode to turn all vector/matrix allocations to fetching preallocated objects from a pool, because a simple math operation could allocate tens/hundreds of vector/matrix objects and GC was slow, but then in newer versions they removed it because Java's GC became fast enough.

It is an argument that Java can do arenas like some other languages, while providing the productivity of a tracing GC for the rest of the non critical path code.