I went to every major Canon forum and a lot of people are saying that the 5D3 focuses slower with the AF-Assist beam on when using at least a 600ex with the camera in dim or dark situations when this topic is brought up. I do club photography and I find it embarrassing to stand around for a long time trying to get a focus lock. Sometimes people walk away from the shot or look at me like I am crazy. The only way I know how to focus faster in situations is to play with the AF-point and move it towards the red light on the subject. Lets make a petition or something because I also own a 7D and it focuses in an instant with the same flash. It is the camera!