To speed up the multiplication operation, higher radices are used. For instance, in the Intel's Itanium poulson processor, radix-16 multiplier is incorporated. Increasing the radix, decreases the number of partial product generators (PPG). As a consequence, the critical path becomes shorter. But increasing the radix has a negative effect on the amount of logic ressources required inside the PPG. So there is a tradoff which is quite critical. Refer to my papers on this issue (available in researchgate).