What is the hydraulic power unit design? Is it only one pump? Is it a variable-displacement pump (swash plate), or a fixed-displacement pump with VFD, or a fixed-displacement pump with constant-speed motor and a relief valve?
If the hydraulic power unit is maintaining pressure with a relief valve, then you have the potential to save a lot of energy. A relief valve is very inefficient. The standard method of improving it is to use a swash-plate pump instead. That way, the motor will do less work one the system reaches pressure. I believe a fixed-displacement pump with a VFD is be somewhat more energy efficient, but the initial cost is more.
On a high-performance motion control system, it is very difficult to reduce the energy that is dropped across the valve. Reducing the system pressure may help, but there is a limit to how far it can be reduced and still maintain enough flow to perform the desired motion.
In recent years, research has figured out how to drive a cylinder directly from a hydraulic pump, without going through a servovalve, thereby saving large amounts of energy, but that works well for large human-controlled systems such as excavators, and not so well for systems that require precise, high-frequency control.
Waiting to hear more on what exactly your hydraulic power unit is.