Free text search – Indicate faster option

I have a free text box that provides the ability to search for other users.

You can type anything you like into the box (part of the name, email address, job title...etc) and it will provide a list of results.

However the search is fairly slow, takes around 30 seconds (working on improving this).

So I detect if what is entered is a username, if so I can get the user instantly.

How do I indicate to the user that they can search for anything they might know, if however they know the username it is a much better option, because it is orders or magnitude faster?

I've thought of just writing a little note to say this, but I wondered if there's a more natural way to suggest it.