Let’s talk about what movement efficiency really is. Efficiency is using as little effort as possible to accomplish a movement. But that doesn’t really help understand how to be more efficient, does it?
You create efficiency by using the minimum amount of tension and the maximum amount of relaxation needed to complete the movement. It sounds odd to talk about relaxation during something like deadlift, but it is important.
Obviously, as the movement becomes more demanding the tension required becomes higher and the amount of relaxation used will become lower, but for most movements, we won’t need that level of tension so there’s a lot of room for more relaxation.