Caching with logged in/not logged in or ecommerce basket views (idea for solution?)

[eluser]surfgatinho[/eluser]
I really want to use some caching as the app I am building is getting fairly complicated with lots of queries and lots of joins.

Anyway, the problem is there is a user menu if they are logged in or a login box if they are not. CI caching doesn't deal with that, it just cache's the whole page.

A possible solution, which I am about to try in a minute would be to use javascript/ajax to spit out the login box / user menu.

It's not even going to impact on SEO because it's not really somewhere you want the search engines to be going.

I'll let you know how I get on