It sounds more like a problem with unreal expectations. What frame of reference tells you that the machine should have more power?
All you can do is check the hydraulic pressures and cycle times. I don't have either specification here with me but many times you can check other machines of the same size for a general statement on cycle times. I know for instance that standard cycle time for boom up in larger excavators is around 4 seconds. If your cycle times and pressures are at factory specification there isn't a problem with the machine.
Your machine is pretty old speaking in mini excavator terms. It is also a gray market machine. I haven't looked at one of those in years but as I recall they even had gear pumps.