Complexity comparison of an adder and a multiplier
The time required to perform additions and multiplications varies with the amount of circuitry one devotes to them; conversely, the amount of hardware varies according to the required speed.  If you're trying to figure out which algorithm would require more hardware to implement at some minimum acceptable speed, or which algorithm could be made to run faster with a given amount of hardware, you'll need to define your constraints.  In general, multiplies can be performed almost as fast as additions, but the hardware required to perform multiplications at the maximum possible speed is much more expensive than the hardware required to perform them more slowly.