Comment by Calavar

For that scenario you can use a pool allocator backed by a fixed size allocation from an arena. That gives you the flexibility to allocate and free resources on the fly, but with a fixed upper limit to the lifetime (e.g. the lifetime of the level or chunk). Once you're ready to unload a level or a chunk, you can rewind the arena, which is a very cheap operation (as opposed to calling free in a loop, which can be expensive if the free implementation tries to defragment the freelist)