If you feed it an N byte array it will have to allocate an N+16 array and memcpy. If you're reading from the network/disk/etc then there is no need to copy if y

If you feed it an N byte array it will have to allocate an N+16 array and memcpy. If you're reading from the network/disk/etc then there is no need to copy if you can allocate the larger array directly.