Hi,
The performance tracker reports that the search process finishes within 0.12 seconds in average. It means that there is either a hold-up process before or after the search, either due to an error or for some other reason. Unfortunately there are no error messages in the responses, so I can’t see why. It does not seem to be dependent on the configuration either, I have no idea what’s holding the response back.
Can you also provide temporary FTP details so I can debug the full ajax request step-by-step? I might be able to uncover the exact line of code or plugin causing this insane delay.