The Quick Edit function often makes it a lot easier to modify a large chunk of data in SharePoint. If your list contains some “People and Groups” fields, however, the Quick Edit function may not be so quick for you, because for each of the rows, you need to spend a little bit of time waiting for SharePoint to find the user you’re looking for.
An easy way to get around SharePoint’s lack of speed, shall we say, is to use a person’s email address. By entering an email address into the People or Groups field, you speed up the “search” function that SharePoint uses to pull your information from the Active Directory. Since the email addresses are unique, it should also find your users fairly quickly.
While it seems counter-intuitive to some people – “Why can’t we just use their names?” – it really does make it faster. If you’re copying and pasting several rows at once, you don’t want SharePoint to get hung up on that People and Groups field that you need.