[maemre]

Manual memory management is much more predictable (which is really nice for interactive/real-time programs), it does have nontrivial runtime overhead: malloc and free aren't free (pun slightly intended), and often costlier than a bump allocator most moving/copying GCs use (just increment a pointer and have a very branch-predictable conditional to check OOM). Also, moving/copying GCs increase data locality by bringing live objects closer, which is more cache friendly.

I agree that manual memory management is much more predictable than garbage collection, I just wanted to touch on the nuances of the memory overhead of manual memory management.

Also, if the program creates lots of short-lived objects (which is often the case), a generational garbage collector would be pretty fast because it will reclaim/move a few objects rather than deallocating many objects. An arena collector or allocating on the stack might be better (and manual methods) in this scenario though.