This repost is the result of additions suggested by kamara, kunzite1, and phoenixdreaming.
When loading any part of a journal (or community) using the S2 style system, if you receive an error message similar to the following "The message "Error running style: Died in S2::run_code running FriendsPage::print(): Style code didn't finish running in a timely fashion. Possible causes:Infinite loop in style or layer", then the Style code on that page could not completely load. This could be a problem with the Style code, but may also indicate that LiveJournal servers are too busy to process the Style. Please try refreshing the page. If this error persists and you own the journal, you may wish to check over your Style code for errors or to change the way in which you customise. If the Style code stops running at a particular section or feature, you may wish to remove or disable that feature. Common solutions include removing the mini-calendar, reducing the number of entries per page, or using the lj-cut tag to shorten long entries.
kamara thinks that it should go after the section on caching.
Further reading section should also include:
FAQ 75 for lj-cut tags
FAQ 170 + FAQ 171 for the "change the way in which you customise"
FAQ 172 for advanced S2 resources.