I sometimes use a timer instead of a loop to add an item every 0.01 seconds.
This gives the control back to the user while the list is still populating, so the user doesn’t need to wait for the whole list before starting to look and maybe click at the first items.
Then I add a little javascript that uses the scroll events to fetch another batch of items from the server and restart the timer, so I get a responsive and dynamic loading of large lists.