Cassandra constantly stopped to check and make sure she wasn't being heard, which constantly slowed her picking the lock, but it was a precaution she was willing to take. As soon as she was out her room, she made sure to lock the door. Seconds could be precious, she knew. Who to go to first? She knew all their names, but didn't know much about them all. 

Still....she tried to find Lucy's room, avoiding the room that she had just seen Vlad go into. She made the effort to be silent, and when she reached a door, she quickly tried to unlock it, once more using her lunar energy in a very fine, solid thread