Hi Dave,

First thing I'd try would be to shut off comets, then asteroids,
to determine which is the problem. Odds are that the asteroids are the
real culprit. There just aren't as many comets as there are asteroids,
by a factor of a thousand or so, and Guide has some good tricks in it
to avoid having to waste much time on most of the comets.

But asteroids are another matter. The current MPCORB contains about
325 000 of them. On a 900 MHz machine, when you turn on MPCORB,
there's about a seven-second pause before the asteroids turn on. During
that time, Guide computes some information about where the asteroids
will be over a one-day span. It can then show asteroids with blazing
speed, as long as the date/time remains within that span. But if you
change the time by more than twelve hours in either direction, you get
that seven-second pause again. I have some ideas for handling this
problem, but none of them seem very good: they wouldn't provide much
speedup, and/or would be horribly complicated or consume most of a hard
drive.

(If you find that Guide is _always_ sluggish, even when you don't
change the date/time, then you should get the current software from the
Web site. Older versions didn't do this "compute data for a 24-hour
span" routine, and had to do all the math from scratch each time the
screen was drawn or an object was clicked on.)

-- Bill