There is already a provision in the act for institutions to get an extension when there are a large number of records and providing the disclosure would unreasonably interfere with the operation of the institution. That already exists in the current legislation.
Evidence of meeting #75 for Access to Information, Privacy and Ethics in the 42nd Parliament, 1st Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was c-58.
A video is available from Parliament.