It looks like there are still a few examples of this old issue knocking around (oddly enough, 2 requests came up at once recently, one of which is
here) so I thought a quick post about it so that people know what's going on.
We only ever observed this problem with portfolorid, I believe but there's no fundamental reason it couldn't happen with other styles. The way it presented was that the main SB page would load correctly but gallery pages would time out if the gallery had any pictures in it.
The cause, if I remember rightly, was that it was possible to set a thumbnail size in the customization wizard that hadn't been defined in the style (this is a sentance that is only likely to make sense to you if you know S2 for scrapbook and even then only possibly). This basically got the parser confused and resulted in a timeout. To resolve, we would just tell the user to use a different style as their default. I think it would also be possible to resolve it by getting them to remove their customizations, as the default should work but the orginal outbreak was so long ago that I'm not sure if we tried that - anyone who wants to experiment in this area should feel free if we get any more requests.
The option has since been removed from the customization wizard so we can't get new cases of this but if someone hasn't changed their customizations for a long time then it's still possible that this is the bug their experiencing so if they open a request where their galleries time out, try getting them to change their style and see if it resolves things.