I'm interested in this as I agree we need to improve load efficiency, but I'm not exactly understanding what case you would like to improve.

As far as I know second level caching should be used transparently if it's available (enabled on the specific relation), and also as you point out ORM should not initialize lazy loaded entities if we are only reading the ID.
It would be very useful if If you could describe the specific mapping which doesn't work as expected.

Note that this might depend on your mapping: if you don't mark your relations and collections as lazy, then it's natural that they will be loaded eagerly.