Haven't replied on this topic before now, because I really have nothing to add.
It does seem a little slow, but not (to me) terrible. It has to handle a lookup of over a thousand presets, so it will not be immediate. These units are not PCs and have less computing power allocated to the display.
An H8000/7600 will be slower in this respect than a 7000 or Orville, as these do not have the sorting and filtering capability of the later units.