In live view the shutter is wide open and the mirror is up. To take a picture, the shutter needs to close, then open for the proper shutter time, then it closes to end the exposure, then it re-opens to continue live view. So there is a lot going on, some of it before the actual exposure, giving you some lag time. But the actual exposure can be any available shutter speed. As far as camera life-time shutter count (from exif data), a live view snap counts as 2 shutter actuations.