Hi,
It depends from what criteria do you use when restricts admins with limited privileges.
For example, if you block access to some posts, you can use block model and block 1000 posts by some criteria, but allow 5. Apparently much more memory is required to get those 1000 posts ID list than just 5 posts ID.
URE caches results of db queries using WP transients, thus for some time memory consuming may be postponed.
The most simple workaround: increase available memory for logged in users with some role. Use
ini_set('memory_limit', '512M');
and wp_login action.
