Seems you are compressing this cube for the first time. As there are lots of request to compress so its going to take a lot of time. These jobs does tends to take a lot of time so you have to make sure you scheduled this out of business hours i.e. better to be done on weekends.
Also i would suggest to compress the requests in pieces initially . You have to plan it and thereafter you can schedule process chains to run on weekends.
Thanks