syxton had this patch included on one of his branches.
It adds a new setting for the navigation to control the automatic expansion and loading of courses in the my courses branch when it is active.

The my courses branch is expanded by default only when the user is viewing their My Moodle page, or any page masquerading as it (not sure if there are any).

Quoted from a comment Matthew made later in this issue in regards to how the change came about:

In our case, we had professors who have large amounts of courses, some very old courses that are creating a long list. They use the My Home area and didn't like that a big "ugly" list was staring at them all the time. On a lesser note, the change also speeds up the load of our pages because it doesn't have to run through the course tree again. But it was a request that we had and I thought it might be worth sharing.