I never been very fond of Firefox, it has always been a very slow browser on Mac and has had problems with panoramas since Quicktime time.
I just got the update to Firefox 5 and the loading of multiresolution KRpanos is very slow.
I have a 30megabit fiberconnection so normally in Safari any panoramas load completely within a couple of seconds.
After somme tests I found that also OPERA has similar behavior as Firefox.
The problems seems to be at least partly in loading multiresolution when you have autorotation applied.
This is a 4 level multi with 512 pixels tiles and it starts zoomed in and then zooms out while autorotating.
http://www.panoramas.dk/2010/carlbloch/
Just load it and let it rotate all the way around. In Safari and Chrome the loading bar is gone within a couple of seconds on my connection and I never see the preview except for a 1 sec glimpse at start.
But with Firefox and Opera the previews keeps coming up and they never disappear until I click in the image to stop rotation. The loading bar just stalls and it will continue for at least a minute if I do not stop the autorotation.
Here is a version with autorotation disabled.
http://www.panoramas.dk/2010/carlbloch/noautorotation.html
It helps but it still takes 10-15 sec before the loadingbar disappears and even then I se previews when I rotate the panorama 180 degrees.
I have not tested this on Windows yet.
Hans