In extreme cases, this can become uneasy and then you need a mental model of what is traceable and what GC "roots" to add. If it's not GC-reachable it gets coll

In extreme cases, this can become uneasy and then you need a mental model of what is traceable and what GC "roots" to add. If it's not GC-reachable it gets collected. But in most cases, most people will likely just need custom allocators, or just malloc. You can generate arbitrarily less garbage in D progressively. Mixed allocation strategies is still nice because whatever is in GC memory doesn't need an owner (it has a global owner). Nowadays, the D GC is really unlikely to be a problem whatever your performance requirements. It isn't a problem for corporate users, as you can see on the parent link. Besides the GC performance increased in the last few years.