Long-lived things end up in older generations and aren't traversed much during GC, which is the moral equivalent of being statically allocated.
There's overhead if you mutate old objects in a GCed system due to card marking.
Lisp vectors are vectors of pointers, so there's still an overhead of dereferencing through it. Presumably the objects being pointed to end up compacted together, eventually.
I should have been more clear; I meant using vectors as arena allocators, so that all of your data ends up stored contiguously with no extra indirection.
There's overhead if you mutate old objects in a GCed system due to card marking.
Lisp vectors are vectors of pointers, so there's still an overhead of dereferencing through it. Presumably the objects being pointed to end up compacted together, eventually.