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 which fields you want to give permission, then select Profile or Permission Set and select field list.
After that click on "Fetch field Permission" Button. The results are shown in the form of a table on the page. Give permission and then click on the "Save" button. Hurray !! you successfully assigned permissions.