Performance issue when loading user notifications from profile

Issue Summary

From a user's profile, when the user click on "Notifications", the page will take a very long time to load.

Steps to Reproduce

1. In a normal Bamboo instance, create a large amount of plans (in the thousands).
2. Many users will need to mark these plans as favorite.
3. Create a large amount of notifications (in the thousands).
4. Make sure many of these notifications have "watchers" as recipient type.

Expected Results

Page loads within seconds.

Actual Results

Page may take minutes to load, even timing out.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available