Another hidden penalty of some (but not all) GCs is that they can't handle interior pointers so anything that is addressable need to be separately allocated. So

Another hidden penalty of some (but not all) GCs is that they can't handle interior pointers so anything that is addressable need to be separately allocated. So not only you have more allocations to track and more space and time overhead, you also add indirections where they are not needed. Of course a Sufficiently Smart Compiler can remove the overhead, but well...