That's basically the same thing as the line I mentioned above. If you have an immediate dictionary result, then displaying a little "searching for" infobox might actually slow it down slightly (particularly on an older, slower E Ink display), or at least
feel slower to some people even if it isn't necessarily so. But you don't have to wait for the highlight to disappear before tapping. The point is actually to reduce visual disorientating by leaving some markers around the interface.
A bit like how this highlights the element you were linked to:
http://jsfiddle.net/nnyxwh84/