Mass Assign Permission provides you with a quick solution. For example, for Field-level Security, click on "Mass Assign Field Permission Tab" and select an object whose fields you want to give permission, then select "Profile or Permission Set" and select the field list.
After that, click on the "Fetch field Permission" button. The results are shown on the page in the form of a table. Give permission and then click on the "Save" button. Hurray !! You were successful in assigning permissions.