This Bug Report indicates that in world testing reveals that the most recent update has slashed list based performance of scripts. One large club owner has reported to me that there has been a 50% reduction in the ability of servers to handle large numbers of avatars, and that "agent time" has passed "script time" as the major generator of lag, as seen through the view statistics -> time panel.
Second Life Insider has been all over this story already. And complaints have been logged by users on the official blog.
I am going to call around and confirm this with as many large sim owners as I can lay my hands on. The bug report seems fairly clear and the people complaining are in a position to know: Jesse Murdoch of Bad Girls and Arsheba Nasu, the tech contact for Arsheba.
I guess this counts as news, though according to one person, repeated requests for help from Linden Labs and opened tickets, have yielded nothing, with LL denying that anything has happened at all.
This hits people who run large content centers, such as clubs, harder. Almost everything in a club worth doing, sploders, greeters, sensors, uses a list to manage the data. Lists are relatively bad in sl to begin with, with features that even script novices like myself feel the lack of. The visible effects are reduced script handling, time dilation spikes even in lightly loaded sims, and the inability of resets to cure performance issues. The spike represents a four fold increase in "agent time."