The topic-title says it all. When i change the menu and save it, it clears the whole cache of the site what is a problem...
Also on this topic:
http://wordpress.org/support/topic/plugin-wp-super-cache-nav-menu-update-clears-all-blog-cache?replies=6
I saw somebody with the same problem 1 year ago and was helped with the dev-version. But i think it never reached the production-version?