I don't know much if anything about your specific tractor loader, but here is some general info on hydraulics
Found this trying to find more about the hydraulics on your loader,
The working of a hydraulic pump can slow down after continuous work hours. Mostly, the sluggishness in the pump is caused by the
hydraulic compensator valve.
You need to get in touch with your mechanic and have your tractor checked because only an expert can
detect the faults in valves and fix them accordingly.
However, fixing the valves is a
temporary solution. Farmers who keep using the machines with the faulty valves have to suffer the damage of the complete breakdown of the New Holland Workmaster 50 tractors.
Also according to tractor data there are four different loaders that fit your tractor.
I believe your issue has been explained very well in previous posts. but would like to help you possibly understand the whys.
Most hydraulic cylinder have a single rod coming out of the barrel to do work. This rod displaces area of the cylinder so the rod end of the cylinder has less "capacity" than the barrel end, therefore with a given flow the cylinder will retract faster than extend due to the different capacities of the cylinder. Some manufacturers use a cylinder that the rod comes out both ends IH did this on the steering of utility tractors. If the had used a cylinder with only the rod coming out of one end the wheels would turn quicker one way than the other.
Some manufacturers put restrictors in the lowering side of the loader so it could not have an uncontrolable or too fast of a drop. You may want to check and see if if equipped the restrictor did not get installed on the wrong line.
Food for thought: There are two ways to speed up hydraulics. 1 reduce the size of the area that is being filled. Of course this may also reduce the amount of lift. 2. Increase the volume of pump output. Note not pressure, but the Gallons Per Minute (GPM) This would fill the cylinders faster and increase speed. And finally it does not matter which way a cylinder is installed. As your bucket cylinder it still will have to fill the rod end to curl and the barrel end to dump. They only difference in speed may be a loaded bucket will dump faster than an empty bucket due to the weight "pulling" on the cylinder, That is unless there is a restriction in the line.