This is the processing that you are typically trying to speed along when testing out new settings. Group Policy background refresh happens naturally in the background on a periodic basis. The default timer for new updates is 90 minutes. Every hour and a half, workstations will check in with Active Directory and ask whether or not anything in Group Policy has been updated. If not, it won't do anything. If there have been changes, then those policies changed will be re-processed on the client machine, thereby putting the new settings into place.