If you are allowed to use many transistors, you could create a carry look-ahead adder which would be faster. ;) There are more ways to speed up your CPU, like

If you are allowed to use many transistors, you could create a carry look-ahead adder which would be faster. ;) There are more ways to speed up your CPU, like identifying instructions that can be executed independently and issue them in parallel, use caches to speed up loading, etc.