iMovie stuck optimizing, Help!

I am trying to move a 1.83 MB mp4 video file into iMovie. It says its going to take 34 hours to optimize and I want to stop it but I can't while its optimizing. I have two questions first, how do I shut it down/stop iMovie? Second, How do I speed the process of moveing this file into iMovie. Its a film I torrented and I need to use clips of it in a progect. This is the information I have on the file: MPEG-4, 1.82 GB, 1080p, dimensions: 1920-1040.