Hate to break it to you, but Codeshaper would not have started t his thread if it was just a client-based problem. This is a Turbine issue, and has been a Turbine issue.
Do not try to minimalize Turbines involvement in this by just telling people to buy better computers. Turbine did that themselves after the dataserver move that all lag from there on was only client based, the backlash and the evidence pointed in a different direction.
Many of us have been here long enough to know what gameplay options and graphic options to adjust in order to minimalize the client based part lag as much as possible, and we understand that an online game WILL have lag; however, what has been going on since update 9 and the "hotfix" has been across the board for the majority of players. Just ask some of your guildies: Tassy, Rakky, Tsta and they will express some of the same lag issues that everyone else is talking about here.