Query for reverse link on user_load ?

The current implementation of the reverse link for nodes referencing a given user (on the user's profile page) perform queries as soon as user_load(), and for all userref fields, whether the 'reverse link' option has been checked or not.
User_load() being a possibly costly (and non statically cached) operation, and the advertised feature being only 'display links on the profile page', I'm wondering if we should :
- do the additional queries only when actually viewing the user page
- do it only for userref fields for which the 'reverse link' option has been explicitly set.

Additionnally, the current code to query nodes referencing the user will break if different user fields live in the same per content type table' - thus marking as a bug. No time for a patch tonight :-)