What do you mean by 'significant amount of content'? Inserting html is of course faster than rendering in the client, but the javascript involved here is not slow - I haven't seen anything over 15 ms yet for rendering a fairly complicated page (I'm using a resig-style microtemplate, which is probably faster).

Are you perhaps constructing the nodes on the document, instead of doing them off the tree and then inserting/replacing them all at once?