chrisseaton is talking about the bump-pointer allocator in a modern GC, not an implementation of malloc/free. The performance characteristics are quite different.
In a generational copying system an object that is bump allocated and then is dead before being copied out of the young generation is indeed cheap - dead objects in the young generation don't need to be freed or even looked at in any way because the space for the young generation can simply be reused after everything is copied out of it. The slow part is elsewhere.
In a generational copying system an object that is bump allocated and then is dead before being copied out of the young generation is indeed cheap - dead objects in the young generation don't need to be freed or even looked at in any way because the space for the young generation can simply be reused after everything is copied out of it. The slow part is elsewhere.