Hi,
first of all thanks for this very handy plugin - I would have expected something like that being core of WP, but very cool somebody took care of it :-)
However, one suggestion regarding performance: Maybe you can add a check around the whole code whether a user is on the admin site...so for "normal" visitors there is no need to register all your actions.
if(is_admin()) {
// your whole plugin code
}
Not sure, if that makes a big difference, but maybe for sites used heavily it does...