I think, and this is just my speculation, so take it with a grain of salt, that the problem with raid lag now has everything to do with the trait tree revamp. Before the trait trees, there really weren't that many debuffs that you wold see on a boss, and these were applied really only by the support classes (maybe 1-2 rows of debuffs). When Turbine did the trait trees, they gave pretty much every class numerous debuffs that can be applied (usually by an RNG) to a boss, so the boss ends up with 15 rows of debuffs that have to be processed and whose icons have to be sent down to your client if you have the boss selected. The reason why I think this is that we tend not to see this kind of lag on instances that have lots of mobs (like Wound wing in OD), or if we enable skill target forwarding and don't select the boss. It seems as though Turbine didn't properly think through the performance impact of giving every single class tons of debuffs that could be applied to a single target.
Is this speculation in line with other folks' experience? Do you get less lag on raids with multiple targets? Does skill-target forwarding work?
Duruleth - 100 RK, Durindor - 100 Grd, Durselm - 76 LM, Durscap - 100 Cpt, Henckel - 79 Champ, Durbear - 100 Beorning, Anglin - 67 Mins