I've mentioned the new Avatar Complexity feature before, for example when I had to abandon a new tutu I had bought for an SL party because the designer, though doing a beautiful job, had made the tutu so complex with prims that my whole avatar would not rez to the other people in the club.
I've seen a couple of other avatars lately who were unaware that they could not be seen by other people as their outfits were overloaded with detail. So a couple of nights ago I headed over to that very popular and always crowded Muddy's Music Cafe not only to have a good time, but to see how many avatars were not rendered in my viewer and would just appear like solid colours. Just as I thought, there were a couple of people whose complexity score about their heads was over 500,000, when other people who were rezzed properly were around the 38,000 to 49,000 complexity mark, If your outfit gives you a very high complexity number it's best to try to lower it by changing any items you think may have too much detail, such as hair for instance and then to ask your friends if you are visible to them. To see Complexity on Firestorm, go to Advanced Menu - Performance Tools - Show avatar complexity information. Anyway, here is a video by Torley Linden that explains how it all works: