This could definitely be tricky to troubleshoot. A few questions come to mind that might help me get started:
When you say difficulty repainting, do you mean as it relates to the laggy behavior, or are there other repainting issues like ghosting or artifacts?
No Ghosting or Artifacts. Behaves more like the FPS drops to 1 FPS
How does the lag act - does it seem like a slideshow - the whole screen updates at once but the updates are too far apart? or is it more like part of the screen updates, then another part of the screen updates, then another part of the screen updates, until everything is updated?
Whole screen updates but they are far apart. When sitting in PoK, I can see all the NPCS and PCs move but at something close to 1 FPS
If it starts lagging after a few minutes - does the amount of time before it starts to lag seem to be fairly consistent, or is it pretty variable?
Time it takes seems fairly consistent.
Once it starts lagging, does it seem to get worse the longer it runs, or does it get to a certain level of lag and sort of stay there?
Reaches a point then stays there
Have you seen it start happening while you're in different zones, or have you pretty much been in the same place when it happened?
Happens in all zones I have visited