Performance wise, it is a wash. In C, allocating (malloc) and freeing objects can be costly, since heap bookkeeping tends to be more complicated. With managed memory, allocation usually means just incrementing a pointer, but you pay for it eventually when you run out of memory and the garbage collector kicks in. The fact is that V8 uses garbage collection for better or worse.
They go on to outline how V8 divides the heap into manageable chunks and the processes through which garbage collection is enacted. Check out the post.