I use this feature many times every session, and haven't had the issues you are having. My first thought is you have an addon that is freaking out, try going addon free a while for testing and see if that improves it. Do you have enough RAM? I say 4gig minimum for 5 box. Have you set maxfps to ~50 and maxbkfps ~15? Do you need to set core affinities? (I think you only need to do that on a quad core with Vista) How many monitors/graphics cards (card RAM?) Have you set your graphics options for your toons to minimums?