Allocation cost in region is just pointer update, quite cheap. Deallocation is constant. You will get speedup if you can replace large number of allocations wit

Allocation cost in region is just pointer update, quite cheap. Deallocation is constant. You will get speedup if you can replace large number of allocations with arena. In gc languages you don't have luxury of specifying custom allocators for selected parts of the program. But the main argument was that tracing gc hides all of this from you and you can't profile your program explicitly see which callstacks contribute to large deallocations. Just because gc hides it, defers and spreads in time, doesn't mean it's zero cost – on contrary tracing will have more overhead. In vast majority of programs power consumption overhead is not relevant though, if it's traded for programming ergonomics, it's a win.