speeding up search page

I'm looking for some advice for ways to decrease the log in delay.
When a user logs in, the first thing they are presented with is a
search page.  The fields on this page are determined by the client and
often there are between 15 and 25 fields.  The fields are editable
combo boxes that show unique values to help them figure out what to
search on.  I'm caching all of the unique values on the server-side,
but my hunch is that it takes a long while to transfer all the data in
the models of the combo boxes.

To increase performance...
* Is there a way to lazy load the combo box data?
* Aynchronously load the combo box data?

kind regards,
Cameron