Here is a thread that talks about some times for building/exporting a slide show. (about halfway down)
Also make sure that you have your energy saver settings to;
computer sleep: never
Put the hard disk(s) to sleep.. no
Message was edited by: Tony Gay
This is a really late response, but for others curious about this: yes, this surprising slowness is my experience too. If I were to build a similar slideshow by hand in Motion for instance, it would export almost faster than real time. So Apple perhaps should look into this - and at least put in some progress feedback. Now you don't know - is it gonna be 30 minutes or over night?
Now you don't know - is it gonna be 30 minutes or over night?
It will largely depend on the theme you are using. A simple "Classic" or Ken Burns slideshow without too many animations will render far quicker than for example the "Places" theme. With the added complication of network access required for the maps it can take indeed all night to render a relatively short slideshow with the Places theme.