Ever notice that the Second Life grid's performance tends to suddenly drop at midnight, Pacific time? That's the hurly-burly of batch processing. Stipend payments, group disbursements and traffic calculations. In fact, some parts of the traffic calculations system is so dense and arcane that processing the previous 24 hours worth of data doesn't always even finish within 24 hours.
Linden Lab have been making noises about simplifying the traffic system for about three years, and there have been a number of under-the-hood tweaks to the algorithms during that time. In fact, the majority of Second Life users believe that the new system that has been announced has actually already been in place since 2006 (partly because the existing system can appear that way, as an edge-case of some overly-simplistic testing methodology).