do you mean a delay in the TID screen signal? Or the actual audio indication as well? Because if you just meant the TID screen, this is norm for the XLT. They have an annoying delay between the time you pass over the target, to a second later when the TID appears on the screen. Other detectors are more instananeous. A lot of people didn't like the XLT for this reason.
But if you meant simply audio signal, I dunno. I don't recall that having a delay.