mod_expires to the Rescue

OpenLayers and MapBuilder apps each require download of a mass of javascript, and a significant wait. Developers are looking into javascript on demand, which is interesting, but the problem is pretty much solved in most cases by Apache's mod_expires. Drop this .htaccess into your javascript library root:

ExpiresDefault "access plus 1 month"

and your clients will cache the bulky javascript for up to a month.

Update: this works better if you're using the single-file build of OpenLayers.