Dynamic power is primarily affected by activity. The more work that the design is doing, the more energy it ends up needing. As the speed to complete work in the design increases, the power required increases.
To save dynamic power, either you slow down the design (reduce clock speeds), try to reduce voltages, or attempt to cut down design activity.
Reducing capacitances in the design is another important aspect of saving power, which typically can be accomplished with efficient implementation or by tweaking processes.
