tree widget is very slow on IE but fast on firefox.... any ideas?

I'm using active widget tree to create a folderlike structure on my page. It does have many folders to load but it takes way too long to load on IE. It takes around 60-70 secs to load on IE and just around 10-15 sec on FireFox
10-15 secs is reasonable considering the size of data to load, but 60-70 sec on IE is just too ridiculous. Does anyone have any idea on how to improve performance on IE???