Dual Boxing Interment FPS dips

Intermittent FPS lag dual boxing.So I upgraded my hardware sucessfully, and now I can run 2 accounts on a single Phenom II X4 940 B.E , 8GB ram, 4890 1gb. Using Keyclone, I can seamlessly use dual displays with ease. But not everything is perfect. I hope it could be though, with your help. Using Vista 64

I can run 2 accounts at 1680x1050 using the above machine at the least 100+ FPS using everything maxed except shadows (i dont care much). Which is awesome. BUT , when running two accounts, I intermittently get this FPS lag - more like an FPS 'dip' every 10 seconds or so to around 20FPS that lasts around 10 seconds each time. Needless to say that is pretty dang annoying. Everything else is fine even in cities though I haven't checked any wotlk zones since my chars aren't high enough yet. I tried to tinker with the display settings, turning off sound, etc, but the problem is still there. I even enabled write/caching, disabled the page file in windows, but nothing to fix it.

What could this be due to?

As of right now I'm downloading Windows 7 RC to see if that would change anything. But I wanted input from the pros here.

Ah, I should have posted this in support. Sorry about that.

did you create keyclone commands to launch your wows? (it makes life a lot easier)

when you do that, make sure to set the maxfpsbk and maxfps fields. anything over 50 fps is overkill (the avg human eye sees about 42fps). the maxfpsbk is the number of frames your wow will try to get when it is not active. this saves your cpu and gpu loads of headaches.

personally, i 5-box on 2 screens @ 1680x1050 and get 15/42 (maxfpsbk 15 maxfps 42) almost constantly. (cpu stays around 50%)

also... the fps does depend on what it is trying to be rendered. if you have something a bit more complex walking around, it might reduce the fps until it is out of frame.

yeah, ive done that . keyclone's a great program for its convenience and of course much more. under vista it didnt stop the lag. after upgrading to windows 7 the problem went away. Too bad in general the whole OS feels less responsive than vista, but thats why i guess its a pre-release. Its not bad though. thanks alot.