Bob,
We have a number of launch pages that each have many comboboxes, each with multi-select allowed.
We've also found that when developed with the ususal IBI tools, background processes are run before painting the launch page that query the required tables to obtain the values to put into the launch page's combo/dropdownselect boxes. To populate some of our boxes required querying 1.5M row tables, and this, as you've found slows displaying the page.
Our solution involved a multi-step RCaster job run overnight that developes the content of all such boxes for our whole population of launch pages. For each select box the RCaster job produces a boxname.htm file that is included into the lauch page with "!IBI.FIL.boxname;".
This really speeds up the loading of the launch page (except for our one page that includeds a combobox with 12K rows!).
This solution is only valid for lists whose content need not be 'real time', but even that demand can be approximately satisfied by running the RCaster job more often than once a day; hourly perhaps.
If you're interested in this solution I can post the text of the overnight job, etc.
WIN/2K running WF 7.6.4
Development via DevStudio 7.6.4, MRE, TextEditor.
Data is Oracle, MS-SQL.