4boxer to 5, FPS drops massive?

[Acidburning]

done 3 versions: 4 ele shammys, dk, 3 rets, and a mixed group. Decided a few months ago to buy a 5th account, move a character over. Spent a day setting up, but got slammed at work, and now, I am back setting everything up after these massive patches.

my problem is, 1 account seems to lag, hard. It will drop to under 1fps ?? Most of the time it's the 5th account, but when I swap, it could be any one of the others. I have moved this team to UC, because of the new influx at org. But even when zone into a random heroic, one still drops to 1fps?

running 4 was never an issue, and I didn't think adding a 5th and trying to pve would be this bad.

All accounts are bumped down to the lowest video setting in wow & sound is off.

Any thoughts? random settings I am some how missing?

edit: FYI, I have disabled all addons, even Jamba and the problem continues.
edit2: When I log 1 out, the 4 are fine, everything sitting at 20+ FPS, no real lag between the 4 other accounts.

System:
Processor: AMD Phenom(tm) 9750 Quad-Core Processor 2.40 GHz
Memory (RAM): 8.00 GB
System type: 64-bit Operating System
Display adapters: ATI Radeon HD 3600 Series
Windows Vista Ultimate
ISboxer

When I watch the windows task manager, it doesn't seem to get past 5GB

thanks,

acid