Haven't had a problem, and I'm sure hoping I never will.
Actually, when I open stuff in other tabs, I notice that the 'vista's loading your crap circle' is there, spinning, for quite a while...but that may just be because I have about 10 other tabs and a like number of other programs up. I never noticed, since I never went to the next tab until I was done with the current one, giving it anywhere from a minute to ten to load, but now that I've gone and looked, it's there. Doesn't affect anything else, though. Does your firewall not like the new design?