By lag, I mean everything is extremely slow. I'm pulling 2-5fps while my players easily pull 50-60. I can't move with reliably. Typically when I open an inventory I can manipulate items without much trouble.
I have 4GB dedicated to MC and looking at the F3 screen i'm never actually using more than 2.
I've recently started noticing system-wide symptoms and, after some extensive testing, I have determined that I have a bad stick of RAM and my CPU seems to be compromised.
Time for a rebuild!