Hosting html in silverlight: IE vs FF/Chrome

Hello everyone,

I am currently developing a portal in silverlight 4, which requires facebook integration (facebook like box among others). First I encountered a problem with embedding a html frame (like box) into the page. I finally achieved this by placing an additional <div> in my aspx page (that hosts the silverlight object) and placing an iframe with the desired source in it. It works.
The problem is when we want to scroll / resize the page. I implemented dynamic changes to the div's top and left properties to move the iframe accordingly to the silverlight page.
Now the actual problem:
The solution works almost perfecly in IE 8.0. It's firefox and chrome that cause trouble. In both of the above the iframe flickers during scrolling/resizing. It even changes it's position to the opposite (horizontal) from time to time. I also noticed lower performance when scrolling. Is there some other way to host html in silverlight (in ff/chrome)? Maybe some additional js in .aspx to distinguish browser type and change the way it is embedded?
PS. I also tried telerik's html host control. It turns out that it hides the html content when moved. Though I also noticed lower performance in ff/chrome (ie works fine still).

Thanks in advance for any help :)