The Finishing toolpath will always cut the entire model. It always makes one pass at full depth.
The Purpose of the roughing toolpath is to remove a majority of the material prior to the finishing pass. This allows you to use smaller bits that may not be capable of making a full depth finishing pass by themselves.
You need to increase the feedrate to decrease the time. Or increase the stepover value.
3D toolpaths can take a very long time, as you've seen.