Disabling GC is wildly inefficient without making sure you don't have garbage because allocation will slow down the application to human scale. The magic is more in the no-allocation code than in the disable GC side. It is very annoying in Java because any non-primitive is boxed type. Object pools etc. Problem is it's easy to start in Java, but then you hit a wall. JNI has huge overhead. Exasperating. But hard to argue, sometimes if you don't start in Java you never get the problem because you never manage to bootstrap.