as Dan is suggesting, use what is usually called
'autosuggest' to help
users find the user they want by letting them type in first
2-3
characters of the name and showing them a short list of users
with names
starting with those characters, instead of having them scr0ll
through
4500 list items to select a user.
after that you do not really need to use ajax to populate
your form
fields - instead have a form in a different page and relocate
the user
to that page passing the id of user selected in the
autosuggest list.
this is easier than using ajax to populate various form
fields, though
if you are on cf8 it is fairly trivial, too with data
bindings or cf
javascript proxies. it all in the docs if you need more
info...
hth
Azadi Saryev
Sabai-dee.com
http://www.sabai-dee.com/