I think it would be useful to have a search function when viewing all threads so that people don't have to search through hundreds or thousands of threads to see if they are going to make a duplicate. Thoughts?

Rejected.
Just use find on page will do. A search function is a heavy load on the server (maybe. Not a tech wiz. Remembered it being discussed somewhere else).
Also those wouldn't bother searching before making a new thread.

use ctrl + f