A client-side extension run on the client computer to implement Group Policy on that computer.
In GMPC settings can be modified for slow link, background processing and process the policy even if there are no changes. These can be configured under Computer Configuration/Policies/Administrative Templates/System/Group Policy.
By default, client-side extensions are not processed over a slow link. The “Allow processing across a slow network connections”, changes this default and makes it so that client-side extension is processed over a slow link.
Every 90 minutes + an offset , group policy refreshes in the background. The option “Do not apply during periodic background processing” prevent the system from updating the effected items until the next user logon or system restart.