These problems are not new. I remember so much complaining last year at a similar time, and the official excuse at that time was the integration of the upcoming expansion (Riders of Rohan) into the game, which most of us know is bs, since the lag still strongly persists in the game today, especially on highly populated servers. I spend most of my Lotro days on creepside on Vilya server, and to be honest, the lag is present, but not overwhelming (there is a problem in keeps with many npcs, combined with effects from certain classes, like RKs, LMs, Spiders etc.), however, the last year when I mostly played on freepside on the same server, and then a few months after the Rohan expansion, when i transferred on Brandywine, the lag was absolutely horrible. Horrible as in a game breaking way, where the frustrations got so high, that raids were disbanded because of it.
Turbine is well aware of the problem, but figures that the resource investment cost for fixing it surpases the overall benefit for them.
Unfortunately, nothing will happen.
Vilya: Healadder (defiler, R10), Kommisar (stalker, R7).
Snowbourn: Superserial (warleader, R8), Steelstack (reaver, R6).
Brandywine: Manvet (champion, R10 - Retired); Stargash-1 (reaver, R12)