Company ABC grew organically and now their single-area OSPF network has an unacceptably slow convergence...

Company ABC grew organically and now their single-area OSPF network has an unacceptably slow convergence time after a topology change. To address the slow convergence time, they want to introduce a multiarea OSPF design and implement address summarization at the area border routers, which option should be their main concern about this redesign?