Problem: .html file slows down a .swf file

It’s really strange that when a flash movie clip running under the IE with a .html file, the movie clip seems got slow down so much and is not as smooth as running under the flash player even they are in the same screen size.
Anyone knows how to solve this problem?

is the movieclip thats running in a .swf thats loaded in another .swf? because all the framerates have to be the same…

There’s only one single .swf file running and does not contain any loadmovie command