When a user with access to a large number of question bank categories (typically 1,000+), such as a category manager, tries to move questions using the bulk Move to... action, the system fails silently. Specifically, the core_get_fragment AJAX request—responsible for populating the autocomplete field with available question banks—returns a 500 Internal Server Error, leaving the field empty.

Apache logs indicate the error is caused by memory exhaustion.
Increasing the PHP memory_limit from 128M to 512M mitigates the issue.
However, even with increased memory, the request takes 3–5 seconds to complete.

Steps to Reproduce

1. Log in as a user with access to 1,000+ question bank categories.
2. Navigate to a quiz or question bank.
3. Select one or more questions and choose the Move to... bulk action.
4. The Move the selected questions to... modal is empty and does not display Question bank or Question categories