As always, it depends. For most cases, Garbage Collection is faster than malloc/free. On some platforms, Java can allocate objects in like 3 instructions. It does this because garbage collection allows for optimizations that simply aren't possible using manual memory allocation.
Of course, there are apps that require manual memory management, but they are becoming few and far between.
Of course, there are apps that require manual memory management, but they are becoming few and far between.